CLDR-8081 Add names for traditional Myanmar calendar

[mapmeld]

This PR helps fulfill the ICU / ICU4C calendar request ( https://github.com/unicode-org/icu/pull/630 ). It's necessary to add a name for the calendar to BCP47, and names for the months to CLDR.

On a project in Myanmar in 2015, I observed that people may offer the lunar calendar date for their birthday. Our team used reference books to go between the Gregorian calendar and the traditional system. Online references: https://en.wikipedia.org/wiki/Burmese_calendar#Month ; https://saraniya.com/myanmar/myanmar-calendar/ ; https://archive.org/details/burmesearakanese00irwiiala/page/8/mode/2up Interactive: https://yan9a.github.io/mmcal/

Understanding the name: the ICU ticket refers to the Myanmar calendar, and dates should match the calendar maintained by the Myanmar Calendar Advisory Board.

Understanding eras: following mmcal's example to use eras to represent pre-colonial, colonial, and post-independence calendar systems (years are continuous and have the same abbreviation, ME).

Understanding 15 months:

• There are 12 standard months, the first is Tagu and the last is Tabaung
• During "little watat" years, Waso is followed by a 30-day leap month named Second Waso
• The Burmese New Year often occurs in the middle of Tagu, meaning that "Tagu 1350" could refer to the beginning or end of that year. To avoid confusion the name Late Tagu / Hnaung Tagu can be used at the end of the year. Late Tagu and Late Kason (another possible split month) bring the total to 15 month names.

I'm unable to complete the tests on my machine:

[ERROR] Failed to execute goal on project cldr-code: Could not resolve dependencies for project org.unicode.cldr:cldr-code:jar:46.0-SNAPSHOT: Failed to collect dependencies at com.ibm.icu:icu4j:jar:76.0.1-SNAPSHOT: Failed to read artifact descriptor for com.ibm.icu:icu4j:jar:76.0.1-SNAPSHOT: Could not transfer artifact com.ibm.icu:icu4j:pom:76.0.1-SNAPSHOT from/to githubicu (https://maven.pkg.github.com/unicode-org/icu): authentication failed for https://maven.pkg.github.com/unicode-org/icu/com/ibm/icu/icu4j/76.0.1-SNAPSHOT/icu4j-76.0.1-SNAPSHOT.pom, status: 401 Unauthorized -> [Help 1]

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Hooray! The files in the branch are the same across the force-push. 😃

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