Feature: Add registry override variable support, and add additional messaging around this in logs

[Schnitzel]

this allows to override an existing password in the .lagoon.yml

[Schnitzel]

@shreddedbacon @tobybellwood would love your feedback on this. I personally feel this is a good thing as in the very beginning I think we did not have the possibility to add the password to the API and so there might be lagoon users out there that have the password hardcoded, Having a default say to search for a password in the API in this form: ${PRIVATE_CONTAINER_REGISTRY}_PASSWORD might not be a bad practice?

[shreddedbacon]

I like the idea, but I think using ${PRIVATE_CONTAINER_REGISTRY}_PASSWORD might not be ideal. If you call your registry test in the .lagoon.yml. You create test_PASSWORD variable in the API under container_registry scope. But if you use a TEST_PASSWORD variable in the project already, you won't be able to add the container registry override, as we constrain name/project as unique key, even though the scopes would be different, and the case is different.

$ lagoon add variable -p example-project -N test_PASSWORD -V mypassword -S container_registry
Result: success
Project: example-project
ID: 4

$ lagoon add variable -p example-project -N TEST_PASSWORD -V myotherpassword -S global
Error: graphql: (conn=204366, no: 1062, SQLState: 23000) Duplicate entry 'TEST_PASSWORD-1' for key 'name_project'
sql: insert into `env_vars` (`environment`, `id`, `name`, `project`, `scope`, `value`) values (DEFAULT, DEFAULT, 'TEST_PASSWORD', 1, 'global', 'myotherpassword') - parameters:{}

Might be better to use REGISTRY_${PRIVATE_CONTAINER_REGISTRY}_PASSWORD to make it clear it is a registry password, and then the likely hood of potential clashes is lower

I know for the particular customer impacted by this problem it won't matter if the REGISTRY_ prefix was there, but just thinking about others potential users

[shreddedbacon]

Closing in favor of #133

[shreddedbacon]

Reopening, #133 contains other PRs not confirmed for merging yet

[shreddedbacon]

This has been running for one of our customers for some time now with no issues.