SMTP password should be stored in a secret instead of config map

[ppawlowski]

Description

The main goal of this task is to store password, used for SMTP authentication, in the secret object.
Additionally, next to passing value via values file/inline, the possibility of using an external secret for smtp password should be added.

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#290

Epic/Story

No response

[joepavitt]

Hey @ppawlowski could I be a pain and request you add an appropriate sizing to this please, and then a rough "Expected" date on when it would be done - not going to be a hard deadline, just trying to size issues and workload