RFR: 8295650: JFR: jfr scrub should warn if an event type doesn't exist

[Erik Gahlin]

Hi,

It's easy to do a typo when using the 'jfr scrub' command. For example, a user may type "jdk.InitialEnvironmentVariables", "jdk.EnvironmentVariable" or "InitialEnvironmentVariables" and believe events have been removed from recording file when they should have typed "jdk.InitialEnvironmentVariable" to filter out sensitive data. 

To help users, a warning message is now written if an event filter doesn't match metadata available in the recording.

Thanks
Erik

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Commit messages:
 - Remove file and imports
 - Initial

Changes: https://git.openjdk.org/jdk/pull/10779/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=10779&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8295650
  Stats: 70 lines in 3 files changed: 52 ins; 11 del; 7 mod
  Patch: https://git.openjdk.org/jdk/pull/10779.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/10779/head:pull/10779

PR: https://git.openjdk.org/jdk/pull/10779