An attempt to normalize some of the function names in build.zig. Normalize add*Dir to add*Path. Also use "Library" instead of the "Lib" abbreviation.
The PR does not remove the old names, only adds the new normalized ones to faciliate a transition period.
Tests a scenario where the linker line has the following:
```
main.o libA.a libB.a
```
where `main.o` pulls a symbol from `libB.a`, which in turn is
dependent on a symbol from `libA.a`.