Implement deprecation info API for joda-java migration

[pgomulka]

There is currently no warning for joda-java pattern incompatibilities.
We should warn users who migrate from 6.x to 7 that their pattern might no longer work in 7 unless they update their mappings.
Pattern can be used in:

• index mapping
• pipeline processors: date processor and date index name processor

Incompatible pattern specifiers:

• Y year-of-era in joda should be updated to y year-of-era in java.time. Y means week-based-year in java.time
• y year in joda, should be updated to u year in java.time. The difference between year and year-of-era is that year can have values <0 for years before the era.
• x week-yearin joda should be updated toYin java.time.x` means zone-offset in java.time.
• C century is no longer supported in java.time
• Z time zone offset/id has the same meaning in java.time as it had previously in joda. However it will fail when parsing Z in a date. For instance 2019-05-09T14:24:00.000Z (in Zulu/UTC time) will fail parsing. X could be used instead and correctly parse this date.
• z time zone text - Will print Z for Zulu given UTC timezone. Previously joda was printing UTC for utc timezone.

[elasticmachine]

Pinging @elastic/es-core-infra

[pgomulka]

closed by #42659 (7.x) and #41956 (6.8)