- Use range for loop to iterate over instructions.
- Emit generated code in anonymous namespace instead of `llvm` and
reduce the scope of this to just the type declarations.
- Emit generated tables as static constexpr
- Replace code to search in operand table with `std::search`.
- Skip the last "null" entry in PrefixTable and use range for loop to
search PrefixTable in the .cpp code.
- Do not generate `WebAssemblyInstructionTableSize` definition as its
already defined in the .cpp file.
- Remove {} for single statement loop/if/else bodies.

Also use brace initialization and emplace to avoid explicitly 
constructing std::pair, and the same for std::tuple.

Change WebAssemblyDisassemblerEmitter to use const RecordKeeper.

This is a part of effort to have better const correctness in TableGen
backends:


https://discourse.llvm.org/t/psa-planned-changes-to-tablegen-getallderiveddefinitions-api-potential-downstream-breakages/81089

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

These are unnecessary since C++17.

```
find llvm/utils/TableGen -iname "*.h" -o -iname "*.cpp" | xargs clang-format-16 -i
```

Split from #80847

This is (IMHO) cleaner and (objectively) more strongly typed than using strings.

A follow-on patch will do the same for IsWasm64.

Differential Revision: https://reviews.llvm.org/D125713

The logic around IsCanonical previously used getAsString and compared to
"1". Just using getValueAsBit is simpler.

This commits removes TableGens reliance on managed static global record state
by moving the RecordContext into the RecordKeeper. The RecordKeeper is now
treated similarly to a (LLVM|MLIR|etc)Context object and is passed to static
construction functions. This is an important step forward in removing TableGens
reliance on global state, and in a followup will allow for users that parse tablegen
to parse multiple tablegen files without worrying about Record lifetime.

Differential Revision: https://reviews.llvm.org/D125276

Based on the output of include-what-you-use.
It's an utility directory, so no much impact on other code areas.

clang++ -E  -Iinclude -I../llvm/include ../llvm/utils/TableGen/*.cpp -std=c++14 -fno-rtti -fno-exceptions | wc -l
before: 4327274
after:  4316190

Related discourse thread: https://llvm.discourse.group/t/include-what-you-use-include-cleanup
Differential Revision: https://reviews.llvm.org/D118466