chore: enhance docker config injection

[niranjan94]

Short description of what this resolves:

Moves SPA app config to a meta field & injects config into that at fastboot runtime.

Checklist

• I have read the Contribution & Best practices Guide.
• My branch is up-to-date with the Upstream development branch.
• The acceptance, integration, unit tests and linter pass locally with my changes
• I have added tests that prove my fix is effective or that my feature works
• I have added necessary documentation (if appropriate)

[niranjan94]

Here is an overview of what got changed by this pull request:

Issues
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+ Solved 46
           

Complexity decreasing per file
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+ scripts/replace-config.js  -17
         

See the complete overview on Codacy