[JIRAALIGN-1164] User should not be allowed to create duplicate state mapping

Issue Summary

Users are allowed to create duplicate state mapping causing ambiguous states

Steps to Reproduce

1. Administration > Jira Settings > State Mapping
2. Select a work item type
3. Add nother state by Manually adding same Jira State ID, Jira State Desc

Expected Results

This should not be allowed because this will cause ambiguous states between Jira and Jira Align.

Actual Results

Wrong state is reflected.

Workaround

None.