[clang] [analyzer][NFC] Introduce framework for checker families (PR #139256)

[Donát Nagy via cfe-commits]

NagyDonat wrote:

I have yet another implementation idea where:
- boilerplate is either minimal or nonexistent;
- there is no need to pass an additional string value (the debug name) through the checker registry code;
- the debug name is guaranteed to be the same as the class name.

The minimal-boilerplate version looks  like
```c++
template <typename T>
StringRef getCheckerFamilyName();

#define REGISTER_CHECKER_FAMILY(NAME) template <> StringRef getCheckerFamilyName<NAME>() { return #NAME; }

// in the body of CheckerFamily
  template <typename CHECKER>
  static void _register(CHECKER *Chk, CheckerManager &Mgr) {
    Chk->CheckerBackendName = getCheckerFamilyName<CHECKER>();
    (CHECKs::_register(Chk, Mgr), ...);
  }

// in each file that implements a checker family
REGISTER_CHECKER_FAMILY(MyBeautifulCheckerFamily)
```

If we assume that each checker family class is mentioned in `Checkers.td`, then we can replace `REGISTER_CHECKER_FAMILY` with a header that says

```c++
#define GET_CHECKERS
#define CHECKER(FULLNAME, CLASS, HELPTEXT, DOC_URI, IS_HIDDEN) template <> StringRef getCheckerFamilyName<typename CLASS>() { return #CLASS; }
#include "Checkers.inc"
#undef CHECKER
#undef GET_CHECKERS
```

@steakhal WDYT about this one?

https://github.com/llvm/llvm-project/pull/139256