RFR: 8305582: Compiler crash when compiling record patterns with var

[Aggelos Biboudis]

While `var` is not allowed in record pattern position the compiler was not checking it. This PR address this issue, by introducing the relevant error symbols and error types.

e.g., `if (o instanceof ColoredPoint(var(var x, var y), var c)) { }`

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Commit messages:
 - 8305582: Compiler crash when compiling record patterns with var

Changes: https://git.openjdk.org/jdk/pull/13331/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=13331&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8305582
  Stats: 111 lines in 5 files changed: 102 ins; 1 del; 8 mod
  Patch: https://git.openjdk.org/jdk/pull/13331.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/13331/head:pull/13331

PR: https://git.openjdk.org/jdk/pull/13331