Fix record import via some CSV files

Some CSV files failed to detect as text/csv so the import failed.
ref: https://github.com/gabriel-vasile/mimetype/issues/138

pkg/envoy/csv/decoder.go

@@ -39,6 +39,10 @@ func (y *decoder) CanDecodeFile(f io.Reader) bool {
 	return y.CanDecodeExt(ext)
 }
 
+func (y *decoder) CanDecodeMime(m string) bool {
+	return m == "text/csv"
+}
+
 func (y *decoder) CanDecodeExt(ext string) bool {
 	pt := strings.Split(ext, ".")
 	return strings.TrimSpace(pt[len(pt)-1]) == "csv"