feat: add glob config provider

[swiatekm]

Add a glob config provider and use it in the build. See #708 for the rationale and semantics.

This PR is likely easier to review commit-by-commit, as they're almost completely independent. I'm submitting it as a single PR because I think it's easier to understand with the added context, but if this turns out to hurt more than it helps, I can resubmit separately.

The glob provider is added as a separate package and should be relatively self-explanatory.

The process of adding it to the build is a bit convoluted. We can pass a CollectorSettings struct with a custom ConfigProvider to add our glob provider. However, creating this ConfigProvider requires knowing the config locations, and we need to parse command-line flags. If we could hook into the existing Cobra command, this could be much easier, but as is, we use a workaround to parse what we need.

We unfortunately also need to modify the output of otelcolbuilder, which is done in the Makefile by patching main.go and adding an additional replace clause to go.mod.