ROX-23255: add auth implementation for emailsender API

[johannes94]

Description

Checklist (Definition of Done)

• Unit and integration tests added
• Added test description under Test manual
• Documentation added if necessary (i.e. changes to dev setup, test execution, ...) -> will be added once emailsender is ready to be worked on by others
• CI and all relevant tests are passing
• Add the ticket number to the PR title if available, i.e. ROX-12345: ...
• Discussed security and business related topics privately. Will move any security and business related topics that arise to private communication channel.
• Add secret to app-interface Vault or Secrets Manager if necessary
• RDS changes were e2e tested manually
• Check AWS limits are reasonable for changes provisioning new resources
• (If applicable) Changes to the dp-terraform Helm values have been reflected in the addon on integration environment

Test manual

Additional to the added unit tests I tested the API as follows:

# Start emailservice
export CLUSTER_ID=test
go run emailsender/cmd/app/main.go

# By default the authentication configuration will allow calling the API with a OCM token of any
# engineer in the ACS organization, so make sure you're logged in to ocm.

# Run
curl localhost:8080/api/v1/acscsemail -H "Authorization: Bearer $(ocm token)" -H "Content-Type: application/json" -XPOST --data-raw '{"to":["[email protected]"],"rawMessage":"dGVzdCBtZXNzYWdlIGNvbnRlbnQ="}' -v
# Should yield a 200 status code

# Run the same without auth header
curl localhost:8080/api/v1/acscsemail -H "Content-Type: application/json" -XPOST --data-raw '{"to":["[email protected]"],"rawMessage":"dGVzdCBtZXNzYWdlIGNvbnRlbnQ="}'
# Should yield a 401 status code

# To run tests locally run:
make db/teardown db/setup db/migrate
make ocm/setup
make verify lint binary test test/integration

[openshift-ci]

Skipping CI for Draft Pull Request.
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[openshift-ci]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: johannes94, kurlov

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[openshift-ci]

New changes are detected. LGTM label has been removed.

[johannes94]

/retest

looks like infrastructure related failure