Improve likely class handling for pgo (#51284)

Improve likely class handling for pgo (#51284)

- Move processing of likely class histogram into the JIT
- Fix cases where the devirtualization logic in crossgen2 behaved incorrectly in the presence of likely class histogram data
- Pre-process histogram at crossgen2 time to reduce the size of the pgo data
  - This removes 3/4 of the data from System.Private.CoreLib