[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/tetratelabs/wazero/internal/sys/lazy.go

@@ -0,0 +1,151 @@
+package sys
+
+import (
+	experimentalsys "github.com/tetratelabs/wazero/experimental/sys"
+	"github.com/tetratelabs/wazero/internal/fsapi"
+	"github.com/tetratelabs/wazero/sys"
+)
+
+// compile-time check to ensure lazyDir implements sys.File.
+var _ experimentalsys.File = (*lazyDir)(nil)
+
+type lazyDir struct {
+	experimentalsys.DirFile
+
+	fs experimentalsys.FS
+	f  experimentalsys.File
+}
+
+// Dev implements the same method as documented on sys.File
+func (d *lazyDir) Dev() (uint64, experimentalsys.Errno) {
+	if f, ok := d.file(); !ok {
+		return 0, experimentalsys.EBADF
+	} else {
+		return f.Dev()
+	}
+}
+
+// Ino implements the same method as documented on sys.File
+func (d *lazyDir) Ino() (sys.Inode, experimentalsys.Errno) {
+	if f, ok := d.file(); !ok {
+		return 0, experimentalsys.EBADF
+	} else {
+		return f.Ino()
+	}
+}
+
+// IsDir implements the same method as documented on sys.File
+func (d *lazyDir) IsDir() (bool, experimentalsys.Errno) {
+	// Note: we don't return a constant because we don't know if this is really
+	// backed by a dir, until the first call.
+	if f, ok := d.file(); !ok {
+		return false, experimentalsys.EBADF
+	} else {
+		return f.IsDir()
+	}
+}
+
+// IsAppend implements the same method as documented on sys.File
+func (d *lazyDir) IsAppend() bool {
+	return false
+}
+
+// SetAppend implements the same method as documented on sys.File
+func (d *lazyDir) SetAppend(bool) experimentalsys.Errno {
+	return experimentalsys.EISDIR
+}
+
+// Seek implements the same method as documented on sys.File
+func (d *lazyDir) Seek(offset int64, whence int) (newOffset int64, errno experimentalsys.Errno) {
+	if f, ok := d.file(); !ok {
+		return 0, experimentalsys.EBADF
+	} else {
+		return f.Seek(offset, whence)
+	}
+}
+
+// Stat implements the same method as documented on sys.File
+func (d *lazyDir) Stat() (sys.Stat_t, experimentalsys.Errno) {
+	if f, ok := d.file(); !ok {
+		return sys.Stat_t{}, experimentalsys.EBADF
+	} else {
+		return f.Stat()
+	}
+}
+
+// Readdir implements the same method as documented on sys.File
+func (d *lazyDir) Readdir(n int) (dirents []experimentalsys.Dirent, errno experimentalsys.Errno) {
+	if f, ok := d.file(); !ok {
+		return nil, experimentalsys.EBADF
+	} else {
+		return f.Readdir(n)
+	}
+}
+
+// Sync implements the same method as documented on sys.File
+func (d *lazyDir) Sync() experimentalsys.Errno {
+	if f, ok := d.file(); !ok {
+		return experimentalsys.EBADF
+	} else {
+		return f.Sync()
+	}
+}
+
+// Datasync implements the same method as documented on sys.File
+func (d *lazyDir) Datasync() experimentalsys.Errno {
+	if f, ok := d.file(); !ok {
+		return experimentalsys.EBADF
+	} else {
+		return f.Datasync()
+	}
+}
+
+// Utimens implements the same method as documented on sys.File
+func (d *lazyDir) Utimens(atim, mtim int64) experimentalsys.Errno {
+	if f, ok := d.file(); !ok {
+		return experimentalsys.EBADF
+	} else {
+		return f.Utimens(atim, mtim)
+	}
+}
+
+// file returns the underlying file or false if it doesn't exist.
+func (d *lazyDir) file() (experimentalsys.File, bool) {
+	if f := d.f; d.f != nil {
+		return f, true
+	}
+	var errno experimentalsys.Errno
+	d.f, errno = d.fs.OpenFile(".", experimentalsys.O_RDONLY, 0)
+	switch errno {
+	case 0:
+		return d.f, true
+	case experimentalsys.ENOENT:
+		return nil, false
+	default:
+		panic(errno) // unexpected
+	}
+}
+
+// Close implements fs.File
+func (d *lazyDir) Close() experimentalsys.Errno {
+	f := d.f
+	if f == nil {
+		return 0 // never opened
+	}
+	return f.Close()
+}
+
+// IsNonblock implements the same method as documented on fsapi.File
+func (d *lazyDir) IsNonblock() bool {
+	return false
+}
+
+// SetNonblock implements the same method as documented on fsapi.File
+func (d *lazyDir) SetNonblock(bool) experimentalsys.Errno {
+	return experimentalsys.EISDIR
+}
+
+// Poll implements the same method as documented on fsapi.File
+func (d *lazyDir) Poll(fsapi.Pflag, int32) (ready bool, errno experimentalsys.Errno) {
+	return false, experimentalsys.ENOSYS
+}