perf(nostrand): ship own namespaces as DLLs and stop *load-paths* accumulating roots

[parth-io]

Closes #183, Closes #182

• nos loads its eight namespaces from committed nostrand.*.clj.dll instead of recompiling them at every startup, taking nos version from 4.8s to 2.2s with a deps file and 3.8s to 1.3s without. NostrandMain.csproj stops copying nostrand/**/*.clj into the output.
• refresh/nostrand regenerates those DLLs, exposed as bb refresh-nostrand, run after dotnet build in bb build and bb build-runtime, and added to bb check-drift
• Drops full-aot and Scripts/aot-assemblies.sh as they were unused.
• *load-paths* holds each root once, and set-load-path drops roots it no longer names.

[skydread1]

Two follow-ups outside the diff, both created by this change.

README.md:135 still says "73 DLLs, the compiler and stdlib Nostrand loads at startup". The four files under docs/ moved to 81, this one did not, and the line also needs nostrand's own namespaces named.

CONTRIBUTING.md, the paired bootstrap refresh section lists the triggers as "a stdlib or compiler .clj edit, or a C# runtime change that alters what the compiler emits". After this PR an edit to nostrand/nostrand/**/*.clj re-emits committed DLLs and needs the same paired commit, so it belongs in that list.

One question, not a change request: why is refresh-nostrand in bb build? build-runtime and check-drift already cover it, and as written bb build regenerates 8 of the 81 while the stdlib 28 wait for check-drift.

[parth-io]

@skydread1

README.md

• Fixed the 73
• Added a line about using refresh-nostrand

CONTRIBUTING.md

• Added the note about nostrand/nostrand/**/*.clj as suggested

bb.edn

• Removed nostrand-refresh as mentioned, since check-drift covers it

bb/magic/drift.clj

• Updated the docstrings to mention that refresh-nostrand can also cause drift