Make urInit and urTearDown loader-only

[callumfare]

• Make urInit and urTeardown loader-only, rename them to urLoaderInit and urLoaderTearDown
• Split runtime.yml into loader.yml and adapter.yml
• Add teardown method to layers so they can still cleanly tidy up any state, as they will no longer intercept the loader-only urLoaderTearDown.
• Correct the validation layer's tracking of adapter handles, as urAdapterGet may either create the initial reference or increment it.
• Track the number of in-use adapters in the validation layer. When no more adapters are in use, report all leaked handles. This allows reporting of leaks even if a user does not call urLoaderTeardown

[pbalcer]

Is this being targeted for the upcoming release, so 0.7.1 (or something like that)?

[kbenzie]

Is this being targeted for the upcoming release, so 0.7.1 (or something like that)?

I don't think so, its too big a change for 2024.0 which 0.7.x is primarily for.

I've opened #806 to discuss defining a release process.

[callumfare]

Assuming this passes CI this should be ready to merge now - not sure if we're waiting for anything else before that happens