[jdk21u-dev] RFR: 8320948: NPE due to unreported compiler error

[Satyen Subramaniam]

Backporting JDK-8320948: NPE due to unreported compiler error. The compiler decides not to report compiler error while doing recovery on deferred types - this fix looks into the speculative types of a deferred type and if all the speculative types are erroneous, then use a recovery type as the target type, which later on in the pipeline will imply reporting errors if any. Adds test. Ran GHA Sanity Checks, local Tier 1 and 2, and new `test/langtools/tools/javac/recovery/CrashDueToUnreportedError.java` tests. Patch is clean.

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Commit messages:
 - Backport a9cb120d03e5b2efa244086e213d3b9e4706558a

Changes: https://git.openjdk.org/jdk21u-dev/pull/1696/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk21u-dev&pr=1696&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8320948
  Stats: 35 lines in 3 files changed: 34 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk21u-dev/pull/1696.diff
  Fetch: git fetch https://git.openjdk.org/jdk21u-dev.git pull/1696/head:pull/1696

PR: https://git.openjdk.org/jdk21u-dev/pull/1696