Bootstrap refactoring

[silverdaz]

Since bootstrapping a LocalEGA instance is about generating the relevant configuration files and certificates, we now use a Makefile. Added benefits: we can generate the files in parallel and skip regeneration when possible

Moreover, we introduce a new configuration setting: sensitive values are read explicitly from environment variables, files, secrets or are passed in the configuration file. This removes the unwanted/untraceable overloading of the different settings

Describe the pull request:

• [x] Bug fix
• [x] Functional change
• [x] New feature
• [x] Code cleanup
• [x] Build system change
• [ ] Documentation change
• [ ] Language translation