RFR: 8267262: com/sun/net/httpserver/Filter improve API documentation of static methods

[Julia Boes]

The filter operation `Consumer` that is passed to the factory methods can throw an unchecked exception. This change adds a note on the exception handling in that case. It also adds a clarification to `Filter::afterHandler` on the relation of the filter operation and the client receiving the response.

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Commit messages:
 - address PR comment: update wording
 - Merge branch 'master' into 8267262
 - initial change

Changes: https://git.openjdk.java.net/jdk/pull/4085/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=4085&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8267262
  Stats: 49 lines in 2 files changed: 44 ins; 1 del; 4 mod
  Patch: https://git.openjdk.java.net/jdk/pull/4085.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/4085/head:pull/4085

PR: https://git.openjdk.java.net/jdk/pull/4085