[regression] no language support for snippet files

[RedCMD]

Open any VSCode snippet file

{
	"snippetName": {
		"scope": "scope",
		"prefix": "prefix",
		"body": "snippet ${1:abc}",
		"description": "description"
	}
}

expected:

all language features to be available including:
formating, intellisense, breadcrumbs, schema, squiggle errors, hovers etc

actual:

nothing
other than basic word suggestions and syntax highlighting

cause:

when the snippets language was added in 1.82.0
it was not added to the list of supported languages inside json-language-features
#185017
#189176

[jrieken]

This issue lacks

• a copy paste friendly sample
• repro steps and expected vs actual behaviour

[RedCMD]

tldr: add snippets to json-language-features