<i18n dev> RFR: 8365175: Replace Unicode extension anchor elements with link tag [v2]

[Justin Lu]

> This PR is a cleanup change which replaces anchor element references of the Locale `def_locale_extension` section with the Javadoc link tag. This is a doc only change and is a result of the discussion in the PR of https://github.com/openjdk/jdk/pull/26683.
> 
> This includes one additional conversion of the `legacy_language_codes` section to get rid of all Locale.html anchor element references.

Justin Lu has updated the pull request incrementally with one additional commit since the last revision:

  Missing space in Calendar update

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Changes:
  - all: https://git.openjdk.org/jdk/pull/26996/files
  - new: https://git.openjdk.org/jdk/pull/26996/files/a9208477..5ce79b86

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=26996&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=26996&range=00-01

  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/26996.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/26996/head:pull/26996

PR: https://git.openjdk.org/jdk/pull/26996