Add a databaseSecrets value to populate the DATABASE variables

[sshort]

About the changes

Add a databaseSecrets value to populate the DATABASE_ host, port, username and password vars from secret file.

Closes #183

Important files

Discussion points

[chriswk]

Hi @sshort - thank you for this contribution. Could I trouble you to bump the patch version in the Chart.yaml so our linter succeeds?

[chriswk]

So sorry, but one more iteration seems to be needed, the spelling mistake in the comment in the values file
./charts/unleash/values.yaml:64: enviroment ==> environment
and according to the linter, there's trailing spaces in the file.
I think https://github.com/Unleash/helm-charts/actions/runs/13261095809/job/37078665843?pr=186 should be visible for you as well.

We need these two to pass in order for the more important tests to run (kubeconform and install-charts).
Can I trouble you one more time?

[chriswk]

All green here. Again, thank you, will merge :)