Add bundling of binaries

[GPMueller]

• [x] add simple bundling of shared library dependencies into a dependent's binary directory (optional through CLI flag --bundle)
• [x] re-add the unit test which builds a shared library
• [x] add platform-specific bundling of redistributable packages (into a "build/package" or "build/redist" folder?), e.g. a .app bundle on macOS. CLI flag e.g. --redistributable
• [x] add corresponding documentation
• [x] make the bundling recursive, so that not only the immediate dependencies are bundled
• [x] check for errors after bundling etc

Closes issue #25.

[codecov[bot]]

Codecov Report

Merging #98 into master will decrease coverage by 1.93%. The diff coverage is 61.11%.

@@            Coverage Diff             @@
##           master      #98      +/-   ##
==========================================
- Coverage   80.96%   79.02%   -1.94%     
==========================================
  Files          12       12              
  Lines         972     1173     +201     
==========================================
+ Hits          787      927     +140     
- Misses        185      246      +61

Impacted Files	Coverage Δ
clang_build/project.py	69.95% <25%> (-1.48%)	:arrow_down:
clang_build/errors.py	62.5% <50%> (-12.5%)	:arrow_down:
clang_build/target.py	83.68% <59.34%> (-7.48%)	:arrow_down:
clang_build/clang_build.py	73.46% <70.9%> (+4.15%)	:arrow_up:

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[GPMueller]

I would like to leave the "redistributable bundle" feature as a work in progress, as the design will probably evolve with more use cases.

From my side, this branch is therefore ready to be merged.