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Ex. Adding a feature - Explain what this achieves.-->
#### Description
Builds on
https://github.com/open-telemetry/opentelemetry-collector/pull/12224 and
starts the move of config validation from component to confmap. We can
keep this in `xconfmap` while we determine whether to add the ability to
validate using struct field tags.
I think this has the following advantages:
1. Everything configuration-related is now in confmap instead of split
between confmap and component.
2. We can share things like the mapstructure tag and config key
separator as constants between unmarshaling and validation without
creating dependencies between confmap and component.
~The one uncertainty this creates is what to do with `component.Config`,
which would now be used as a thin alias for `any` without any meaningful
usage in component.~
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#### Link to tracking issue
Fixes
https://github.com/open-telemetry/opentelemetry-collector/issues/11524
Evan Bradley