RFR: 8324750: C2: rename Matcher methods using "superword" -> "autovectorization"

[Emanuel Peter]

Subtask of https://github.com/openjdk/jdk/pull/16620

Matcher::superword_max_vector_size -> Matcher::max_vector_size_autovectorization

Matcher::match_rule_supported_superword -> match_rule_supported_autovectorization

This is to make the naming more general, since these methods can be used by any autovectorizer in the future.

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Commit messages:
 - 8324750

Changes: https://git.openjdk.org/jdk/pull/17583/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=17583&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8324750
  Stats: 34 lines in 12 files changed: 0 ins; 0 del; 34 mod
  Patch: https://git.openjdk.org/jdk/pull/17583.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/17583/head:pull/17583

PR: https://git.openjdk.org/jdk/pull/17583