Apply except as a regex to YAML, and merge relocated sections - #1108

What's changed?

• Fixes spring-boot-22 Recipe messes up logging.file.* in application.yaml #436.

Two separate defects kept logging.file from surviving UpgradeSpringBoot_2_2 in YAML, and left the recipe non-idempotent:

• 1. except was a regex for properties but a glob for YAML. The option is documented as "Regex", and ChangeSpringPropertyKey builds a real regex for the properties path, but it hands the same list straight to org.openrewrite.yaml.ChangePropertyKey, which matches it as a glob. So except: [ .+ ] — the way spring-boot-22-properties.yml says "only rename logging.file when it is a leaf" — excluded nothing at all in YAML, and a logging.file mapping got buried under logging.file.name. The regex is now resolved against the subkeys actually present under the old key, and those literal subkeys are passed on to the YAML recipe, so both formats exclude the same subproperties. This is the mismatch @nmck257 called out on #581.

2. Relocating a property into a section that already exists produced a duplicate key. logging.path → logging.file.path appended a second file: entry next to the existing one, and the next cycle then renamed the property again — so the recipe never converged. Duplicate entries are now merged back together, limited to the segments of the new key so unrelated duplicates elsewhere in the file are left alone.

# before
logging:
  file:
    max-history: 10
    max-size: 10MB
  level:
    org: INFO
  path: ${user.home}/some-folder

# after (before this PR, and still changing on the next cycle)
logging:
  file:
    name:
      max-history: 10
      max-size: 10MB
  level:
    org: INFO
  file:
    name:
      path: ${user.home}/some-folder

# after (this PR)
logging:
  file:
    max-history: 10
    max-size: 10MB
    path: ${user.home}/some-folder
  level:
    org: INFO

ChangeSpringPropertyKeyTest#loggingFileSubpropertiesYaml — replicated in feb28d5 back in 2023 and @Disabled ever since — is enabled and passes. Two smaller tests pin each half of the fix on its own.

Anything in particular you'd like reviewers to focus on?

MergeRelocatedSectionsVisitor deliberately does not reuse org.openrewrite.yaml.MergeDuplicateSectionsVisitor: that one treats any non-newline entry prefix as a comment and bails, so it never merges anything indented, which is every case here. This visitor skips entries whose prefix actually contains a # instead.

excludedSubkeys only inspects direct children of a mapping spelled out under the old key, matching how the except option is documented. A file that writes the old key in flattened form (logging.file.max-size: 10MB) is unchanged in behaviour by this PR.

Related issues this does not close

• ChangeSpringPropertyKey incorrectly copies top level comments and does not preserve initial format for yml property files #353 — the comment half. org.openrewrite.yaml.ChangePropertyKey copies scope.getPrefix() onto the relocated entry (InsertSubpropertyVisitor, line 265); in a multi-document file that prefix carries the document's leading comment, so it gets emitted twice. That needs fixing upstream in openrewrite/rewrite, where it affects every consumer.