Sync to upstream/release/588

[vegorov-rbx]

Type checker/autocomplete:

• Luau::autocomplete no longer performs typechecking internally, make sure to run Frontend::check before performing autocomplete requests
• Autocomplete string suggestions without "" are now only suggested inside the ""
• Autocomplete suggestions now include function (anonymous autofilled) key with a full suggestion for the function expression (with arguments included) stored in AutocompleteEntry::insertText
• AutocompleteEntry::indexedWithSelf is provided for function call suggestions made with :
• Cyclic modules now see each other type exports as any to prevent memory use-after-free (similar to module return type)

Runtime:

• Updated inline/loop unroll cost model to better handle assignments (fixes Loop unrolling can generate absurd amounts of instructions #978)
• math.noise speed was improved by ~30%
• table.concat speed was improved by ~5-7%
• tonumber and tostring now have fastcall paths that execute ~1.5x and ~2.5x faster respectively (fixes concat number with string to convert it doesn't typecheck by default, but it's faster than tostring() #777)
• Fixed crash in luaL_typename when index refers to a non-existing value
• Fixed potential out of memory scenario when using string.sub or string.char in a loop
• Fixed behavior of some fastcall builtins when called without arguments under -O2 to match original functions
• Support for native code execution in VM is now enabled by default (note: native code still has to be generated explicitly)
• CodeGen::compile now accepts CodeGen_OnlyNativeModules flag. When set, only modules that have a --!native hot-comment at the top will be compiled to native code

In our new typechecker:

• Generic type packs are no longer considered to be variadic during unification
• Timeout and cancellation now works in new solver
• Fixed false positive errors around 'table' and 'function' type refinements
• Table literals now use covariant unification rules. This is sound since literal has no type specified and has no aliases
• Fixed issues with blocked types escaping the constraint solver
• Fixed more places where error messages that should've been suppressed were still reported
• Fixed errors when iterating over a top table type

In our native code generation (jit):

• 'DebugLuauAbortingChecks' flag is now supported on A64
• LOP_NEWCLOSURE has been translated to IR