Expose ingest processor functionality within Painless

[danhermann]

Ingest processors that perform operations on inputs that are smaller than documents and return simple outputs should be exposed within Painless via static methods as the lowercase, uppercase, and JSON processors currently are.

• URI parts processor (Expose URI parts processor in Painless #73634)
• Community ID processor (Expose Community ID processor in Painless #73963)

[elasticmachine]

Pinging @elastic/es-core-infra (Team:Core/Infra)

[elasticmachine]

Pinging @elastic/es-core-features (Team:Core/Features)

[rjernst]

Adding ingest processors as methods is much needed. Years ago we added many of them, but there many new processors were added since then.

Is there a specific list that should be added? Without that, this seems like an issue that is not actionable. Additionally, given the method customization options per scripting context, this shouldn't needed any changes in Painless (I'm going to remove the scripting label). If any issues do arise that need modifications in Painless, please create a new issue with the exact need, so that we can track it independently.