[IntelliSense] Expose classRegex search range as an option

[tommy-mitchell]

Related:

• searchRange is too small for cva tailwindcss-intellisense#837
• Expand classRegex search range tailwindcss-intellisense#840
• Increase class search range tailwindcss-intellisense#760

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When using libraries like cva, classes can grow too large for the classRegex search to match within the hardcoded search range. Exposing the search range as a config option has been mentioned/requested before - it'd be great to get it added.