add language option EN-IE

[iCollin]

Partially Fixes https://github.com/smartdevicelink/sdl_core/issues/1942

Depends on https://github.com/smartdevicelink/rpc_spec/pull/320

This PR is ready for review.

Risk

This PR makes no API changes.

Summary

Valid language EN-IE already exists in preloaded_pt json files

Testing

Unit tests and ATF

CLA

• [x] I have signed the CLA

[Jack-Byrne]

These changes will require a proposal. For reference: https://github.com/smartdevicelink/sdl_evolution/blob/master/proposals/0060-support-indian-english-thai.md

[jacobkeeler]

Closed in favor of https://github.com/smartdevicelink/sdl_core/pull/3757