[feature] support processing of (many) more media types (#3090)

* initial work replacing our media decoding / encoding pipeline with ffprobe + ffmpeg

* specify the video codec to use when generating static image from emoji

* update go-storage library (fixes incompatibility after updating go-iotools)

* maintain image aspect ratio when generating a thumbnail for it

* update readme to show go-ffmpreg

* fix a bunch of media tests, move filesize checking to callers of media manager for more flexibility

* remove extra debug from error message

* fix up incorrect function signatures

* update PutFile to just use regular file copy, as changes are file is on separate partition

* fix remaining tests, remove some unneeded tests now we're working with ffmpeg/ffprobe

* update more tests, add more code comments

* add utilities to generate processed emoji / media outputs

* fix remaining tests

* add test for opus media file, add license header to utility cmds

* limit the number of concurrently available ffmpeg / ffprobe instances

* reduce number of instances

* further reduce number of instances

* fix envparsing test with configuration variables

* update docs and configuration with new media-{local,remote}-max-size variables

vendor/codeberg.org/gruf/go-iotools/read.go

@@ -4,6 +4,16 @@ import (
 	"io"
 )
 
+// ReadCloserType implements io.ReadCloser
+// by combining the two underlying interfaces,
+// while providing an exported type to still
+// access the underlying original io.Reader or
+// io.Closer separately (e.g. without wrapping).
+type ReadCloserType struct {
+	io.Reader
+	io.Closer
+}
+
 // ReaderFunc is a function signature which allows
 // a function to implement the io.Reader type.
 type ReaderFunc func([]byte) (int, error)
@@ -22,15 +32,10 @@ func (rf ReaderFromFunc) ReadFrom(r io.Reader) (int64, error) {
 
 // ReadCloser wraps an io.Reader and io.Closer in order to implement io.ReadCloser.
 func ReadCloser(r io.Reader, c io.Closer) io.ReadCloser {
-	return &struct {
-		io.Reader
-		io.Closer
-	}{r, c}
+	return &ReadCloserType{r, c}
 }
 
-// NopReadCloser wraps an io.Reader to implement io.ReadCloser with empty io.Closer implementation.
+// NopReadCloser wraps io.Reader with NopCloser{} in ReadCloserType.
 func NopReadCloser(r io.Reader) io.ReadCloser {
-	return ReadCloser(r, CloserFunc(func() error {
-		return nil
-	}))
+	return &ReadCloserType{r, NopCloser{}}
 }