Allow mounting extra secrets/configmaps

[MPV]

In order to support configuring Maven/SBT with files such as:

• ~/.m2/settings.xml
• ~/.sbt/repositories
• ~/.sbt/1.0/plugins.sbt

...so this chart will support running Scala Steward towards a private registry (such as Nexus).

[MPV]

There are some naming variations/patterns on how different charts do this.

Any preference/suggestion?

(in case I or someone else decides to make a PR)

[jsoref]

Lemme ask internally.

Offhand, I think if you sent a PR, someone would try to think about it. Hopefully it wouldn't be terribly painful to change the strategy if someone expressed a strong opinion.

I've personally seen at least a couple of these formats.

(Sorry for not noticing the PR. Feel free to tag me going forward, but I've added a watch to the repo for the time being...)

[jsoref]

@MPV: are you still up for providing something? I don't think we have a particularly strong opinion.

[mberndt123]

I was trying to do something like this, so I added it:
#11

Then I discovered this issue. I guess that's good as it shows there's a need for this feature.