CodeGenIntrinsic changes:
  - Use `const` Record pointers, and `StringRef` when possible.
  - Default initialize several fields with their definition instead of in
 the constructor.
- Simplify various string checks in the constructor using StringRef
starts_with()/ends_with() functions.
- Eliminate first argument to `setDefaultProperties` and use `TheDef`
class member instead.

IntrinsicEmitter changes:
  - Emit `namespace llvm::Intrinsic` instead of nested namespaces.
  - End generated comments with a .
  - Use range based for loops, and early continue within loops.
  - Emit `static constexpr` instead of `static const` for arrays.
- Change `compareFnAttributes` to use std::tie() to compare intrinsic
attributes and return a default value when all attributes are equal.

STLExtras:
  - Add std::replace wrapper which takes a range.

Refactor of the llvm-tblgen source into:
- a "Basic" library, which contains the bare minimum utilities to build
`llvm-min-tablegen`
- a "Common" library which contains all of the helpers for TableGen
backends. Such helpers can be shared by more than one backend, and even
unit tested (e.g. CodeExpander is, maybe we can add more over time)

Fixes #80647