[experiment] add alternative wasm sqlite3 implementation available via build-tag (#2863)

This allows for building GoToSocial with [SQLite transpiled to WASM](https://github.com/ncruces/go-sqlite3) and accessed through [Wazero](https://wazero.io/).

vendor/github.com/ncruces/go-sqlite3/vfs/api.go

@@ -0,0 +1,175 @@
+// Package vfs wraps the C SQLite VFS API.
+package vfs
+
+import (
+	"context"
+	"io"
+
+	"github.com/tetratelabs/wazero/api"
+)
+
+// A VFS defines the interface between the SQLite core and the underlying operating system.
+//
+// Use sqlite3.ErrorCode or sqlite3.ExtendedErrorCode to return specific error codes to SQLite.
+//
+// https://sqlite.org/c3ref/vfs.html
+type VFS interface {
+	Open(name string, flags OpenFlag) (File, OpenFlag, error)
+	Delete(name string, syncDir bool) error
+	Access(name string, flags AccessFlag) (bool, error)
+	FullPathname(name string) (string, error)
+}
+
+// VFSFilename extends VFS with the ability to use Filename
+// objects for opening files.
+//
+// https://sqlite.org/c3ref/filename.html
+type VFSFilename interface {
+	VFS
+	OpenFilename(name *Filename, flags OpenFlag) (File, OpenFlag, error)
+}
+
+// A File represents an open file in the OS interface layer.
+//
+// Use sqlite3.ErrorCode or sqlite3.ExtendedErrorCode to return specific error codes to SQLite.
+// In particular, sqlite3.BUSY is necessary to correctly implement lock methods.
+//
+// https://sqlite.org/c3ref/io_methods.html
+type File interface {
+	Close() error
+	ReadAt(p []byte, off int64) (n int, err error)
+	WriteAt(p []byte, off int64) (n int, err error)
+	Truncate(size int64) error
+	Sync(flags SyncFlag) error
+	Size() (int64, error)
+	Lock(lock LockLevel) error
+	Unlock(lock LockLevel) error
+	CheckReservedLock() (bool, error)
+	SectorSize() int
+	DeviceCharacteristics() DeviceCharacteristic
+}
+
+// FileLockState extends File to implement the
+// SQLITE_FCNTL_LOCKSTATE file control opcode.
+//
+// https://sqlite.org/c3ref/c_fcntl_begin_atomic_write.html#sqlitefcntllockstate
+type FileLockState interface {
+	File
+	LockState() LockLevel
+}
+
+// FileChunkSize extends File to implement the
+// SQLITE_FCNTL_CHUNK_SIZE file control opcode.
+//
+// https://sqlite.org/c3ref/c_fcntl_begin_atomic_write.html#sqlitefcntlchunksize
+type FileChunkSize interface {
+	File
+	ChunkSize(size int)
+}
+
+// FileSizeHint extends File to implement the
+// SQLITE_FCNTL_SIZE_HINT file control opcode.
+//
+// https://sqlite.org/c3ref/c_fcntl_begin_atomic_write.html#sqlitefcntlsizehint
+type FileSizeHint interface {
+	File
+	SizeHint(size int64) error
+}
+
+// FileHasMoved extends File to implement the
+// SQLITE_FCNTL_HAS_MOVED file control opcode.
+//
+// https://sqlite.org/c3ref/c_fcntl_begin_atomic_write.html#sqlitefcntlhasmoved
+type FileHasMoved interface {
+	File
+	HasMoved() (bool, error)
+}
+
+// FileOverwrite extends File to implement the
+// SQLITE_FCNTL_OVERWRITE file control opcode.
+//
+// https://sqlite.org/c3ref/c_fcntl_begin_atomic_write.html#sqlitefcntloverwrite
+type FileOverwrite interface {
+	File
+	Overwrite() error
+}
+
+// FilePersistentWAL extends File to implement the
+// SQLITE_FCNTL_PERSIST_WAL file control opcode.
+//
+// https://sqlite.org/c3ref/c_fcntl_begin_atomic_write.html#sqlitefcntlpersistwal
+type FilePersistentWAL interface {
+	File
+	PersistentWAL() bool
+	SetPersistentWAL(bool)
+}
+
+// FilePowersafeOverwrite extends File to implement the
+// SQLITE_FCNTL_POWERSAFE_OVERWRITE file control opcode.
+//
+// https://sqlite.org/c3ref/c_fcntl_begin_atomic_write.html#sqlitefcntlpowersafeoverwrite
+type FilePowersafeOverwrite interface {
+	File
+	PowersafeOverwrite() bool
+	SetPowersafeOverwrite(bool)
+}
+
+// FileCommitPhaseTwo extends File to implement the
+// SQLITE_FCNTL_COMMIT_PHASETWO file control opcode.
+//
+// https://sqlite.org/c3ref/c_fcntl_begin_atomic_write.html#sqlitefcntlcommitphasetwo
+type FileCommitPhaseTwo interface {
+	File
+	CommitPhaseTwo() error
+}
+
+// FileBatchAtomicWrite extends File to implement the
+// SQLITE_FCNTL_BEGIN_ATOMIC_WRITE, SQLITE_FCNTL_COMMIT_ATOMIC_WRITE
+// and SQLITE_FCNTL_ROLLBACK_ATOMIC_WRITE file control opcodes.
+//
+// https://sqlite.org/c3ref/c_fcntl_begin_atomic_write.html#sqlitefcntlbeginatomicwrite
+type FileBatchAtomicWrite interface {
+	File
+	BeginAtomicWrite() error
+	CommitAtomicWrite() error
+	RollbackAtomicWrite() error
+}
+
+// FilePragma extends File to implement the
+// SQLITE_FCNTL_PRAGMA file control opcode.
+//
+// https://sqlite.org/c3ref/c_fcntl_begin_atomic_write.html#sqlitefcntlpragma
+type FilePragma interface {
+	File
+	Pragma(name, value string) (string, error)
+}
+
+// FileCheckpoint extends File to implement the
+// SQLITE_FCNTL_CKPT_START and SQLITE_FCNTL_CKPT_DONE
+// file control opcodes.
+//
+// https://sqlite.org/c3ref/c_fcntl_begin_atomic_write.html#sqlitefcntlckptstart
+type FileCheckpoint interface {
+	File
+	CheckpointDone() error
+	CheckpointStart() error
+}
+
+// FileSharedMemory extends File to possibly implement
+// shared-memory for the WAL-index.
+// The same shared-memory instance must be returned
+// for the entire life of the file.
+// It's OK for SharedMemory to return nil.
+type FileSharedMemory interface {
+	File
+	SharedMemory() SharedMemory
+}
+
+// SharedMemory is a shared-memory WAL-index implementation.
+// Use [NewSharedMemory] to create a shared-memory.
+type SharedMemory interface {
+	shmMap(context.Context, api.Module, int32, int32, bool) (uint32, error)
+	shmLock(int32, int32, _ShmFlag) error
+	shmUnmap(bool)
+	io.Closer
+}