ICU-22993 Prototype of Modernize Calendar API

[FrankYFTang]

This PR prototype a Modernize Calendar API

1. We split the creation of calendar calculation and accessing the value into different parts
2. We add a DateFieldsBuilder for the creation
3. We add three interfaces (DateFields, WeekSystem, CalendarLimits) to access the calculated result. All of them are immutable.

We still need to design a better way to support functionality to replace fieldDifference()

Checklist

• Required: Issue filed: ICU-22993
• Required: The PR title must be prefixed with a JIRA Issue number. Example: "ICU-1234 Fix xyz"
• Required: The PR description must include the link to the Jira Issue, for example by completing the URL in the first checklist item
• Required: Each commit message must be prefixed with a JIRA Issue number. Example: "ICU-1234 Fix xyz"
• Issue accepted (done by Technical Committee after discussion)
• Tests included, if applicable
• API docs and/or User Guide docs changed or added, if applicable

[jira-pull-request-webhook]

Notice: the branch changed across the force-push!

• icu4c/source/i18n/calendar.cpp is different
• icu4c/source/i18n/unicode/calendar.h is different

View Diff Across Force-Push

~ Your Friendly Jira-GitHub PR Checker Bot

[jira-pull-request-webhook]

Notice: the branch changed across the force-push!

• icu4c/source/i18n/unicode/calendar.h is different

View Diff Across Force-Push

~ Your Friendly Jira-GitHub PR Checker Bot