RFR: 8285513: JFR: Add more static support for event classes [v2]

[Erik Gahlin]

> Could I have a review that allows code in java.base, which can't have a compile-time dependency on jdk.jfr, to check if an event can be committed without using an event object. See issue for details.
> 
> Testing: 
> - jdk/jdk/jfr
> - tier1 + tier2
> - Tested to implement ThreadSleep event using a static commit method (not part of this changeset)

Erik Gahlin has updated the pull request incrementally with one additional commit since the last revision:

  Fix typos, method and field names

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

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/8810/files
  - new: https://git.openjdk.java.net/jdk/pull/8810/files/b853d559..1e2bfeae

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=8810&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=8810&range=00-01

  Stats: 13 lines in 1 file changed: 0 ins; 0 del; 13 mod
  Patch: https://git.openjdk.java.net/jdk/pull/8810.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/8810/head:pull/8810

PR: https://git.openjdk.java.net/jdk/pull/8810