RFR: 8369595: HttpClient: HttpHeaders.firstValueAsLong failures should be converted to ProtocolException [v6]

[Volkan Yazici]

> Add guards against `HttpHeaders::firstValueAsLong` failures. `H3MalformedResponseTest` is overhauled – migrated to JUnit, reinforced with exception type tests, etc. – but not all `firstValueAsLong` changes are verified with new additional tests. `test/jdk/java/net/httpclient/` tests still do pass.

Volkan Yazici has updated the pull request incrementally with two additional commits since the last revision:

 - Close connection after `Content-Length` read failure in `Http1Response`
 - Insert the redundant `Http3Stream` assert back

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/28431/files
  - new: https://git.openjdk.org/jdk/pull/28431/files/0af344f1..024e355f

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=28431&range=05
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=28431&range=04-05

  Stats: 20 lines in 2 files changed: 12 ins; 6 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/28431.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/28431/head:pull/28431

PR: https://git.openjdk.org/jdk/pull/28431