Add support for plugin path overrides in `protoc-gen-buf-{lint,breaking}`

[doriable]

This PR adds support to protoc-gen-buf-{lint,breaking} for overriding local plugin paths. protoc-gen-buf-{lint,breaking} do not support running remote check plugins, only local.

The primary use-case for this is Bazel, which runs protoc-gen-buf-{lint,breaking} in a sandboxed environment. rules_buf needs to be able to provide path overrides to local check plugin binaries.

If an override for a plugin config is not provided, if the plugin config is a remote plugin, we return an error, otherwise we attempt to use the plugin config as-is.

Fixes #3867

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Build	Format	Lint	Breaking	Updated (UTC)
✅ passed	✅ passed	✅ passed	✅ passed	Jun 16, 2025, 5:54 PM

[doriable]

Tested this against a local Bazel test setup, things look good. Going to merge.