ATO-1864: deprecate orch frontend

[Louisasa]

Wider context of change

We don't use orchestration frontend anymore and we're going to deprecate it, so we need to remove all mention orch frontend.

What’s changed

Remove IdentityProgressFrontendHandler
Remove BaseOrchestrationFrontendHandler
Remove OrchFrontendAuthorizerHandler
Remove OrchFrontend

Manual testing

Deployed to authdev3

Note: won't merge in until other repos have been checked for orch frontend too

Checklist

• Lambdas have correct permissions for the resources they're accessing.
• Impact on orch and auth mutual dependencies has been checked.
• Changes have been made to contract tests or not required.
• Changes have been made to the simulator or not required.
• Changes have been made to stubs or not required.
• Successfully deployed to authdev or not required.
• Successfully run Authentication acceptance tests against sandpit or not required.

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
100.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[james-peacock-gds]

LGTM