allow to set "metadata" in config.yaml without validation constraints

[cforce]

Component(s)

cmd/otelcontribcol

Is your feature request related to a problem? Please describe.

To enable the use of metadata for configuring external programs that manage OpenTelemetry (OTel) collector configurations, it would be helpful to introduce a dedicated section resembling a key-value map. This approach would ensure compatibility without causing the parser or validator to fail.

Describe the solution you'd like

For example:

metadata:
  description: my cfg
  environment: dev
  labelx: "some value"
  labely: 13

I haven't come across anything similar, but perhaps such functionality exists and is just not well-documented or is buried somewhere.

Describe alternatives you've considered

Writing a dedicated extension is kind of overkill, but still might be an option

Additional context

No response