Added configurable `securityContext` and follow `restricted` PSS

[applejag]

Hello! We want to be able to control the securityContext of the 1Password Connect pods to follow our own set of guidelines. Such as we want our pods to use a specific UID.

I've also changed it to follow the restricted Pod Security Standard by default, so people can use the 1Password Connect operator when they have the pod-security.kubernetes.io/enforce: restricted namespace label.

Changes:

• Added securityContext settings to connect chart
• Added securityContext settings to secrets-injector chart
• Changed securityContext to follow restricted Pod Security Standard by default
• Added pre-upgrade to secrets-injector to also update on upgrades
• Added emptyDir for /tmp to secrets-injector as I'm setting securityContext.readOnlyRootFilesystem: true and the glog library requires it to write logs into (changing -alsologtostderr to -logtostderr didn't help)

I've tested this by installing into a test cluster and running the acceptance tests.

Closes #192

[applejag]

Anything I'm missing or that I can help with to get this PR reviewed and merged?

[RuriRyan]

We also need this, as several security policies currently prevent pod creation.

@applejag you probably need to rebase your changed again @edif2008 bump :D

[parsa97]

Could you kindly review this PR? It's a requirement for most of the Kubernetes clusters.

bump: @bo0tzz @edif2008 @volodymyrZotov cc: @applejag

[bo0tzz]

Why did you tag me @parsa97? I have no permissions on this repo.

[ProbstenHias]

Hi, we could also use this change to actually make use of the application.

bump: @edif2008 @volodymyrZotov