Sync to upstream/release/603

[alexmccord]

What's changed?

• Record the location of properties for table types (closes Track the location of FunctionType declarations #802)
• Implement stricter UTF-8 validations as per the RFC (Stricter utf8 library validation rfcs#1)
• Implement buffer as a new type in both the old and new solvers.
• Changed errors produced by some buffer builtins to be a bit more generic to avoid platform-dependent error messages.
• Fixed a bug where Unifier would copy some persistent types, tripping some internal assertions.
• Type checking rules on relational operators is now a little bit more lax.
• Improve dead code elimination for some if statements with complex always-false conditions

New type solver

• Dataflow analysis now generates phi nodes on exit of branches.
• Dataflow analysis avoids producing a new definition for locals or properties that are not owned by that loop.
• If a function parameter has been constrained to never, report errors at all uses of that parameter within that function.
• Switch to using the new Luau::Set to replace std::unordered_set to alleviate some poor allocation characteristics which was negatively affecting overall performance.
• Subtyping can now report many failing reasons instead of just the first one that we happened to find during the test.
• Subtyping now also report reasons for type pack mismatches.
• When visiting if statements or expressions, the resulting context are the common terms in both branches.

Native codegen

• Implement support for buffer builtins to its IR for x64 and A64.
• Optimized table.insert by not inserting a table barrier if it is fastcalled with a constant.

Internal Contributors

Co-authored-by: Aaron Weiss [email protected]
Co-authored-by: Alexander McCord [email protected]
Co-authored-by: Andy Friesen [email protected]
Co-authored-by: Arseny Kapoulkine [email protected]
Co-authored-by: Aviral Goel [email protected]
Co-authored-by: Lily Brown [email protected]
Co-authored-by: Vyacheslav Egorov [email protected]