RFR: 8359472: JVM crashes when attaching a dynamic agent before JVMTI_PHASE_LIVE [v10]

[Francesco Andreuzzi]

> In this PR I add a check to prevent debug builds to crash when an agent tries to attach while the JVM is not in live phase.
> 
> Passes tier1 and tier2 (fastdebug).

Francesco Andreuzzi has updated the pull request incrementally with 10 additional commits since the last revision:

 - c++
 - cc
 - simplfiy
 - mv to attach
 - revert
 - debug
 - backslash
 - quote
 - revert
 - wip

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/27766/files
  - new: https://git.openjdk.org/jdk/pull/27766/files/1363424e..1af09f8b

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=27766&range=09
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=27766&range=08-09

  Stats: 350 lines in 5 files changed: 146 ins; 204 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/27766.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/27766/head:pull/27766

PR: https://git.openjdk.org/jdk/pull/27766