feat: I18n\Time::addCalendarMonth

[christianberkman]

The Time::addMonths() could return an undesired behaviour if a date in the next calandar month is desired. For example, Time(2025-01-31)->addMonths(1) results in 2025-03-03 while a date in february may be desired, or Time(2025-03-31)->addMonths(1) results in a date in May not in April. Of course, this only applies if the dev is looking for a date in the next calendar month (months are weird of course, it is 30, 31, 28, 29 days...? who knows).

Comparison

Initial date: 2025-01-31
+---------+------------+-------------------+
| $months | addMonths  | addCalendarMonths |
+---------+------------+-------------------+
| 0       | 2025-01-31 | 2025-01-31        |
| 1       | 2025-03-03 | 2025-02-28        |
| 2       | 2025-03-31 | 2025-03-31        |
| 3       | 2025-05-01 | 2025-04-30        |
| 4       | 2025-05-31 | 2025-05-31        |
| 5       | 2025-07-01 | 2025-06-30        |
| 6       | 2025-07-31 | 2025-07-31        |
| 7       | 2025-08-31 | 2025-08-31        |
| 8       | 2025-10-01 | 2025-09-30        |
| 9       | 2025-10-31 | 2025-10-31        |
| 10      | 2025-12-01 | 2025-11-30        |
| 11      | 2025-12-31 | 2025-12-31        |
| 12      | 2026-01-31 | 2026-01-31        |
| 13      | 2026-03-03 | 2026-02-28        |
+---------+------------+-------------------+

Checklist:

• Securely signed commits
• Component(s) with PHPDoc blocks, only if necessary or adds value
• Unit testing, with >80% coverage
• User guide updated
• Conforms to style guide

If deemed worthy to include I will write test and documentation.

[christianberkman]

Wrong branch.