knotserver: git: serve all raw content

It's the clients problem now. Also add a tiny exception for svgs since
those get picked up as text/xml otherwise.

knotserver/git/git.go

···
 	}
 }
 
-func (g *GitRepo) BinContent(path string) ([]byte, error) {
+func (g *GitRepo) RawContent(path string) ([]byte, error) {
 	c, err := g.r.CommitObject(g.h)
 	if err != nil {
 		return nil, fmt.Errorf("commit object: %w", err)
···
 		return nil, err
 	}
 
-	isbin, _ := file.IsBinary()
-	if isbin {
-		reader, err := file.Reader()
-		if err != nil {
-			return nil, fmt.Errorf("opening file reader: %w", err)
-		}
-		defer reader.Close()
-
-		return io.ReadAll(reader)
+	reader, err := file.Reader()
+	if err != nil {
+		return nil, fmt.Errorf("opening file reader: %w", err)
 	}
-	return nil, ErrNotBinaryFile
+	defer reader.Close()
+
+	return io.ReadAll(reader)
 }
 
 func (g *GitRepo) Tags() ([]*TagReference, error) {

knotserver/routes.go

···
 		return
 	}
 
-	contents, err := gr.BinContent(treePath)
+	contents, err := gr.RawContent(treePath)
 	if err != nil {
 		writeError(w, err.Error(), http.StatusBadRequest)
 		l.Error("file content", "error", err.Error())
···
 	}
 
 	mimeType := http.DetectContentType(contents)
+
+	// exception for svg
+	if strings.HasPrefix(mimeType, "text/xml") && filepath.Ext(treePath) == ".svg" {
+		mimeType = "image/svg+xml"
+	}
 
 	if !strings.HasPrefix(mimeType, "image/") && !strings.HasPrefix(mimeType, "video/") {
 		l.Error("attempted to serve non-image/video file", "mimetype", mimeType)