agent-config: add support for agent config to cli/manifest and make naming in the api more consistent

[mschuwalow]

resolves #2803
resolves #2818

Wit naming will be updated as part of next pr as that one will need to touch wit anyway

manifest will look like this:

secretDefaults:
   local:
      - path: [ "secret" ]
        value: "a"
      - path: [ "nested", "nestedSecret" ]
        value: 1

components:
  golem-it:agent-sdk-ts:
    templates: ts
    agents:
       ConfigAgent:
          config:
          - path: [ "foo" ]
            value: 1
          - path: [ "bar" ]
            value: "bar"
          - path: [ "nested", "a" ]
            value: true
          - path: [ "nested", "b" ]
            value: [1, 2, 3]
          - path: [ "aliasedNested", "c" ]
            value: 1

[vigoo]

This is not a very understandable help string

[vigoo]

Maybe these parsing functions with their corresponding tests could live in a small submodule in a different file, this one is getting huge

[vigoo]

Two small comments, otherwise looks good