RFR: 8310996: Add JFR event for connect operations [v2]

[Tim Prinzing]

> Adds a JFR event for socket connect operations.
> 
> Existing tests TestSocketEvents and TestSocketChannelEvents modified to also check for connect events.

Tim Prinzing has updated the pull request incrementally with one additional commit since the last revision:

  Added support for connection failure and non-blocking connections.
  
  If an exception is thrown while attempting a connection, the message
  from the exception is stored in the event.  The start time of the
  initial connect call is stored and used when a finishConnect call is
  successful or an exception is thrown.

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Changes:
  - all: https://git.openjdk.org/jdk/pull/21528/files
  - new: https://git.openjdk.org/jdk/pull/21528/files/05227c9d..7113bd75

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=21528&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=21528&range=00-01

  Stats: 91 lines in 4 files changed: 44 ins; 14 del; 33 mod
  Patch: https://git.openjdk.org/jdk/pull/21528.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/21528/head:pull/21528

PR: https://git.openjdk.org/jdk/pull/21528