Overture LSP

This is a fork of Luau LSP with changes specifically for the ungms workflow.

Changes from upstream Luau LSP:

• Added Overture:LoadLibrary support for resolving library types
• Added autocomplete in Overture:LoadLibrary calls
• Added Overture:Get support for resolving specified instance types
• Added autocomplete in Overture:Get calls
• Added support for NamedImports in Overture:LoadLibrary calls
• Added autocomplete for NamedImports in Overture:LoadLibrary calls
• Disabled ImportUnused lint warnings for the Overture variable