feat: add strictContentSecurityPolicy compatibility rule

[markwhitfeld]

Setting the config option of strictContentSecurityPolicy to true will avoid CSP violations

PR Checklist

Please check if your PR fulfills the following requirements:

• The commit message follows our guidelines: https://github.com/ngxs/store/blob/master/CONTRIBUTING.md#commit
• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)

PR Type

What kind of change does this PR introduce?

[X] Bugfix
[X] Feature
[ ] Code style update (formatting, local variables)
[ ] Refactoring (no functional changes, no api changes)
[ ] Build related changes
[ ] CI related changes
[ ] Documentation content changes
[ ] Other... Please describe:

What is the current behavior?

Issue Number: #516 #439

What is the new behavior?

Add a config setting to allow for a strict Content Security Policy.
There will be a small performance hit to selectors because this circumvents an optimisation.
This should be provided in the ngxs options to the root module as follows:

NgxsModule.forRoot([
      ZooState
    ], {
      compatibility: {
        strictContentSecurityPolicy: true
      }
    })

Does this PR introduce a breaking change?

[ ] Yes
[X] No

Other information

[ghost]

@markwhitfeld @amcdnl Can this be merged and released soon. This issue is blocking us and determines whether we move on with this library or another. Thanks for getting the pr up so quickly also. I really want to use this library

[deebloo]

Code looks fine. I don't really understand the issue though so I trust ya 😉