RFR: 8350086: Inline hot Method accessors for faster task selection

[Aleksey Shipilev]

These methods show up prominently on Leyden profiles, as compilation policy asks these properties for methods very often during compile task selection:
 - `Method::invocation_count`
 - `Method::backedge_count`
 - `Method::highest_comp_level`

We can move the definitions for these methods to method.inline.hpp to make them eligible for better inlining.

`interpreter_invocation_count()` method is a bit weird, looks like a leftover from [JDK-8251462](https://bugs.openjdk.org/browse/JDK-8251462). Removing it would prompt more cleanups and renamings in `ciMethod`, so I would leave it for future enhancement.

Additional testing: 
 - [x] Spot-checked Leyden profiles, methods are now fully inlined into hot `CompilerBroker` methods
 - [x] Ad-hoc Leyden benchmarks show minor improvements (< 1%) for time spent in compiler threads

-------------

Commit messages:
 - Fix

Changes: https://git.openjdk.org/jdk/pull/23634/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=23634&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8350086
  Stats: 76 lines in 3 files changed: 39 ins; 33 del; 4 mod
  Patch: https://git.openjdk.org/jdk/pull/23634.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/23634/head:pull/23634

PR: https://git.openjdk.org/jdk/pull/23634