Autodetect parser name with prettier by default (#11558)

Closes https://github.com/zed-industries/zed/issues/11517 

* Removes forced prettier parser name for languages, making `auto`
command to run prettier on every file by default.
* Moves prettier configs away from plugin language declarations into
language settings

Release Notes:

- N/A

crates/languages/src/markdown/config.toml

@@ -11,7 +11,6 @@ brackets = [
     { start = "'", end = "'", close = false, newline = false },
     { start = "`", end = "`", close = false, newline = false },
 ]
-prettier_parser_name = "markdown"
 
 tab_size = 2
 soft_wrap = "preferred_line_length"