[usd] Add custom usage file with CMake and plugin deployment guidance

[JacksonSun-adsk (wingfiring)]

This PR includes:

1. Add a custom ports/usd/usage file because auto-generated usage only mentions TBB::tbb and omits USD library targets.
2. Document find_package(pxr CONFIG REQUIRED), typical link targets, and runtime plugin/plugInfo.json deployment requirements (including Windows).

• Changes comply with the maintainer guide.
• SHA512s are updated for each updated download.
• The "supports" clause reflects platforms that may be fixed by this new version, or no changes were necessary.
• Any fixed CI baseline and CI feature baseline entries are removed from that file, or no entries needed to be changed.
• All patch files in the port are applied and succeed.
• The version database is fixed by rerunning ./vcpkg x-add-version --all and committing the result.
• Exactly one version is added in each modified versions file.

[Billy O'Neal (BillyONeal)]

This does not appear to be where plugins are actually installed based on line 93 ish of portfile.cmake?

[JacksonSun-adsk (wingfiring)]

You're right — my original wording conflated two separate install locations.

I had focused on the core library layout: bin/.dll / lib/.lib (see the Windows block starting around line 105) and the per-library resource registries under bin/usd/ / lib/usd/ (the /usd debug-path fix on line 92, from patch 009). I overlooked the MODULE plugin binaries, which install under plugin/usd/ and are what line 93's /plugin replacement addresses.

Updated the usage to list both paths separately: bin/usd/ / lib/usd/ for the top-level plugInfo.json and core library resource registries, and plugin/usd/ for MODULE plugin DLLs/shared objects.