FIO-9618: Move I18n shim to core

[blakekrammes]

• Move relevant translation strings to core

Link to Jira Ticket

https://formio.atlassian.net/browse/FIO-9618

Description

What changed?

As part of the move to render emails in a core processor instead of formio.js, it was necessary to enable I18n translation in core, thus moving the shim from here to there. Since translation is not directly related to rendering formio components it was deemed fitting to move this to core. I have also moved relevant translation strings to core (many of the errors were already present there and have been removed here). The translations left in formio.js should only relate to frontend concerns.

Why have you chosen this solution?

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Breaking Changes / Backwards Compatibility

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Dependencies

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How has this PR been tested?

Manually

Checklist:

• I have completed the above PR template
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation (if applicable)
• My changes generate no new warnings
• My changes include tests that prove my fix is effective (or that my feature works as intended)
• New and existing unit/integration tests pass locally with my changes
• Any dependent changes have corresponding PRs that are listed above