update e31x hdl containers and add csts reference app

What this MR does / why we need it:

This MR adds support for CSTS for the E31X platform and removes unused i2c worker from assemblies.

CSTS was done based on partner request.

Steps to complete before submitting MR:

• I have read Contribution guidelines

Release Notes

N/A

Changelog

• enh(osp): add csts fsk_modem_app reference to e31x
• bug(osp): removed unused i2c device workers from e31x assemblies

Which issue(s) this MR closes

Closes #64 (closed), #63 (closed)