Add jsonl and snippets suggestion settings

[RedCMD]

fix #209534
still issues with #231224 tho

1. make sure "editor.suggest.insertMode" is set to default "insert"
2. Create .code-snippets file with code

{
	"test": {
		""
	}
}

2. assign language snippets
3. type body within the double quotes ""
   
4. expect quick suggestions to pop up
5. select any suggestion
6. expect the correct number of valid double quotes
   

[RedCMD]

could also combine [json], [jsonc], [jsonl] and [snippets] all into one [json][jsonc][jsonl][snippets]
however there is some priority differences when doing so
iirc @sandy081 knows better

@aeschli added the setting to json orignally dc31a48