Update to use ProviderConfig and introduce ProviderConfigUsage

[hasheddan]

Description of your changes

Updates to using ProviderConfig and introduces ProviderConfigUsage. See individual commits and https://github.com/crossplane/crossplane/issues/1737 for more info.

@displague would love any manual QA efforts y'all can provide given that we don't have CI set up on this repo. I'll keep in draft until I can do some additional testing this evening.

Checklist

I have:

• [x] Run make reviewable to ensure this PR is ready for review.
• [x] Ensured this PR contains a neat, self documenting set of commits.
• [x] Updated any relevant documentation, examples, or release notes.

[displague]

This branch (rebased off master) failes make e2e:

>>>>>>> installing crossplane-provider-equinix-metal into "crossplane-system" namespace
provider.pkg.crossplane.io/crossplane-provider-equinix-metal created
NAME                      READY   UP-TO-DATE   AVAILABLE   AGE
crossplane                1/1     1            1           5s
crossplane-rbac-manager   1/1     1            1           5s

>>>>>>> check kind node cache dir contents
total 44
drwxr-xr-x 3 root root       96 Oct 20 03:12 .
drwxr-xr-x 1 root root     4096 Oct 20 03:12 ..
-rw-r--r-- 1  501 dialout 38400 Oct 20 03:11 crossplane-provider-equinix-metal.xpkg

>>>>>>> check for package pod statuses

--- pods ---
NAME                                                             READY   STATUS              RESTARTS   AGE
crossplane-76d6564c8d-vhckc                                      1/1     Running             0          26s
crossplane-provider-equinix-metal-crossplane-p-dd6bdc748-j7rcx   0/1     ErrImageNeverPull   0          19s
crossplane-rbac-manager-bc874c88b-drhcs                          1/1     Running             0          26s

>>> inspecting pod 'crossplane-76d6564c8d-vhckc'

is not completed, continuing with further checks
check if is ready [✔]
check if is running [✔]
check if has restarts [✔]

>>> inspecting pod 'crossplane-provider-equinix-metal-crossplane-p-dd6bdc748-j7rcx'

is not completed, continuing with further checks
check if is ready
is not ready
>>>>>>> Cleaning up...
Deleting cluster "build-c57adf82-inttests" ...
23:13:07 [FAIL]
make[1]: *** [test-integration] Error 1
make: *** [e2e] Error 2

[displague]

We'll address the e2e issues with this merged in.