refactor: move env vars to json file

[grischperl]

Description

Changes proposed in this pull request:

• all variables moved from .env to config.json
• default location of the config.json
• if desire to change that location, do so by overriding location with an env-var / .env file: AICORE_HOME
• deployment supports mounting secret as a volume

Related issue(s)

#197

[github-actions]

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Note(s) for PR Reviewer(s):

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