feat: add experimental support for generics directive

[ota-meshi]

close #306
close sveltejs/eslint-plugin-svelte#521

generics are not yet marked as experimental features in this parser (Parsing of generics is not opt-in and is always enabled), but before official release, generics should be made experimental if they are still undocumented.

To use it you need to set parserOptions.svelteFeatures.experimentalGenerics to true.

[changeset-bot]

🦋 Changeset detected

Latest commit: 81e4201

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
svelte-eslint-parser	Minor

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[coveralls]

Pull Request Test Coverage Report for Build 8127749354

Details

• 181 of 190 (95.26%) changed or added relevant lines in 5 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.1%) to 91.604%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
src/context/script-let.ts	86	89	96.63%
src/context/fix-locations.ts	30	36	83.33%

Totals
Change from base Build 8094321933:	0.1%
Covered Lines:	2625
Relevant Lines:	2771

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💛 - Coveralls