Track Secret data changes through a hash annotation

[kabicin]

What this PR does / why we need it?:

• Removes Secret resource version based tracking and uses hashes to track Secret changes through an annotation on the PodTemplateSpec.

Does this PR introduce a user-facing change?

• User guide
• CHANGELOG.md

OpenLiberty/open-liberty-operator#828

[leochr]

Kirby and I discussed the following and concluded no concerns:

• The library that's being used to generate the hash doesn't provide a way to get the content from hash. As far as we are aware, there is no way to get content from hash. The hash differs significantly when the content changes slightly, which is good and avoid reverse-engineering content from hash.
• The length of the hash doesn't grow with the content size, so no concern with running out of bounds for annotation.

[leochr]

@kabicin Looks good. Thank you.