8381379: Support std/dstOffset attributes in CLDR's metazone definitions

[gnu-andrew]

This backports support for the dstOffset attribute to the CLDR converter, which is necessary to support new timezone changes in Vancouver (tzdata2026b) and Alberta (tzdata2026c) correctly.

As there are no dstOffset attributes currently in the CLDR data in 25u (version 47), this doesn't yet do much. The test for it will be writing a fix for JDK-8390388: "Cherry-pick tz attributes from newer CLDR data for jdk25u and earlier" which doesn't exist for 27 as it has the newer CLDR with dstOffset.

I actually thought the TimeZoneNamesTest.java changes here might fail without first having the attributes, but this was not the case. So this and its dependency #756 should be able to go in nearly clean and then we get to the more tricky but interesting part. The test passes because of:

+            // This needs to change once TZDB adopts -7 offset year round, and CLDR uses explicit dst offset
+            // namely, "Pacific Standard Time" -> "Pacific Daylight Time"
+            Arguments.of(ZonedDateTime.of(2026, 12, 5, 0, 0, 0, 0, ZoneId.of("America/Vancouver")), "Pacific Standard Time")

which is changed in JDK-8371842: Update CLDR to Version 48.2, which we'll need to backport hunks of for JDK-8390388. With that change & tzdata 2026b (already in 25u), Vancouver should still be reporting "Pacific Daylight Time" in December.

The only adjustments were the copyright header on DateTimeFormatterBuilder.java and the bug ID placement on test/jdk/sun/util/resources/cldr/TimeZoneNamesTest.java, due to 8382020 & 8384043 going in first for the last tzdata update. As it stands, all tests pass as on the previous PR:

$ make -C $HOME/builder/25u-dev run-test TEST="jdk/sun/util/resources"
...
==============================
Test summary
==============================
   TEST                                              TOTAL  PASS  FAIL ERROR  SKIP   
   jtreg:test/jdk/sun/util/resources                    22    22     0     0     0   
==============================
TEST SUCCESS

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Progress

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Integration blocker

 ⚠️ Dependency #756 must be integrated first

Issue

• JDK-8381379: Support std/dstOffset attributes in CLDR's metazone definitions (Enhancement - P4)

Reviewing

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Checkout this PR locally:
$ git fetch https://git.openjdk.org/jdk25u-dev.git pull/757/head:pull/757
$ git checkout pull/757

Update a local copy of the PR:
$ git checkout pull/757
$ git pull https://git.openjdk.org/jdk25u-dev.git pull/757/head

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$ git pr checkout 757

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https://git.openjdk.org/jdk25u-dev/pull/757.diff

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[bridgekeeper]

👋 Welcome back andrew! A progress list of the required criteria for merging this PR into pr/756 will be added to the body of your pull request. There are additional pull request commands available for use with this pull request.

[openjdk]

❗ This change is not yet ready to be integrated.
See the Progress checklist in the description for automated requirements.

[openjdk]

This backport pull request has now been updated with issue from the original commit.

[mlbridge]

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