[Fluent-Bit] Improve Openshift support, allow to use existing SCCs

[thethir13en]

• This commit breaks Openshift compatibility with previous versions
• Add ability to provide existing SecurityContextConstraints name instead of create new one
• Add ability to add annotations for SecrutiryContextConstraints resource, created with the chart
• Add common labels for SecurityContextConstraints
• Improve variables naming

[stevehipwell]

Thanks for the PR @thethir13en, I've added a couple of comments that I think need addressing.

[thethir13en]

@stevehipwell
Updated my commit, with the following:

• keep ".Values.openShift" case to comply with Helm best practices and do not break compatibility with the previous versions of the chart
• add dedicated ".Values.openShift.securityContextConstraints.exisingName", allowing to use existing SCC in cluster
• add ability to provide name for SCC created by Helm chart

[stevehipwell]

I don't think the current chart OpenShift implementation looks right as it shouldn't be possible to get into an invalid state and if you always need a SCC then currently you could.

How about an API like below where you replace <SCC> with a valid out-of-the-box SCC to default to and the logic is that if you set create to true the chart creates a new SCC with either the name input or a default.

openShift:
  enabled: false
  securityContextConstraints:
    create: false
    name:
    annotations: {}
    existingName: <SCC>

[stevehipwell]

@thethir13en could you please rebase this?

[stevehipwell]

LGTM

[stevehipwell]

Thanks @thethir13en, sorry it took so long to get this merged.

[thethir13en]

@stevehipwell everything is fine! Thank you too, for suggestions)