[feature] more filetype support! (#3107)

* add more supported file types to our media processor that ffmpeg supports, update supported mime type lists

* add code comments to the supported mime types slice

* don't check for zero value string, just parse

* remove some unneeded consts which make the code a bit harder to read

* fix test expected instance media mime types, use compact ffprobe json, simple media processing by type

* final tweaks to media processing code

* don't use safe divide where we don't need to

internal/util/ptr.go

@@ -34,6 +34,15 @@ func Ptr[T any](t T) *T {
 	return &t
 }
 
+// PtrIf returns ptr value only if 't' non-zero.
+func PtrIf[T comparable](t T) *T {
+	var z T
+	if t == z {
+		return nil
+	}
+	return &t
+}
+
 // PtrValueOr returns either value of ptr, or default.
 func PtrValueOr[T any](t *T, _default T) T {
 	if t != nil {