RFR: 8319244: implement JVMTI handshakes support for virtual threads [v7]

[Serguei Spitsyn]

> The handshakes support for virtual threads is needed to simplify the JVMTI implementation for virtual threads. There is a significant duplication in the JVMTI code to differentiate code intended to support platform, virtual threads or both. The handshakes are unified, so it is enough to define just one handshake for both platform and virtual thread.
> At the low level, the JVMTI code supporting platform and virtual threads still can be different.
> This implementation is based on the `JvmtiVTMSTransitionDisabler` class.
> 
> The internal API includes two new classes:
>   - `JvmtiHandshake` and `JvmtiUnifiedHandshakeClosure`
>   
>   The `JvmtiUnifiedHandshakeClosure` defines two different callback functions: `do_thread()` and `do_vthread()`.
> 
> The first JVMTI functions are picked first to be converted to use the `JvmtiHandshake`:
>  - `GetStackTrace`, `GetFrameCount`, `GetFrameLocation`, `NotifyFramePop`
> 
> To get the test results clean, the update also fixes the test issue:
> [8318631](https://bugs.openjdk.org/browse/JDK-8318631): GetStackTraceSuspendedStressTest.java failed with "check_jvmti_status: JVMTI function returned error: JVMTI_ERROR_THREAD_NOT_ALIVE (15)" 
> 
> Testing:
>  - the mach5 tiers 1-6 are all passed

Serguei Spitsyn has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains eight additional commits since the last revision:

 - Merge
 - addressed review: (1) removed is_vthread_alive checks; (2) reverted one update
 - addressed review: added check for jdk_internal_vm_Continuation::done(cont)
 - review: get rid of the VM_HandshakeUnmountedVirtualThread
 - remove unneeded ResourceMark from JVMTI GetStackTrace
 - address review: remove fix in libGetStackTraceSuspendedStress.cpp
 - addressed initial minor review comments
 - 8319244: implement JVMTI handshakes support for virtual threads

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/16460/files
  - new: https://git.openjdk.org/jdk/pull/16460/files/a526bd60..2df63547

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=16460&range=06
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=16460&range=05-06

  Stats: 634349 lines in 1310 files changed: 89706 ins; 480412 del; 64231 mod
  Patch: https://git.openjdk.org/jdk/pull/16460.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/16460/head:pull/16460

PR: https://git.openjdk.org/jdk/pull/16460