Add option to override kibana and elasticsearch settings

[jsoriano]

After #1140 it is not possible to manually overwrite stack files, they are written by the stack providers every time a new stack is created. Only the profile settings persist.

For some advanced use cases it can be needed to override kibana or elasticsearch settings.

Provide a way to add additional options to the stack components managed by elastic-package stack.

Related:

• Local files are overwritten since Refactor profiles to decouple them from stack resources #1140
• Persistent local profile configuration was added in Add setting to configure a directory with geoip databases #1211
• Another request for custom settings add ability to set publish ports to config.yml #1262

cc @P1llus

[P1llus]

If elastic-package also manages elastic_agent.yml, for any custom settings, and the original stack files also had that option, maybe that could be useful as well, but ES and Kibana would be the priority from what I know! :)