Mark all library projects as "composite"

[dtinth]

https://www.typescriptlang.org/docs/handbook/project-references.html

[codecov-io]

Codecov Report

Merging #521 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #521   +/-   ##
=======================================
  Coverage   82.04%   82.04%           
=======================================
  Files         167      167           
  Lines        5129     5129           
  Branches       68       68           
=======================================
  Hits         4208     4208           
  Misses        903      903           
  Partials       18       18

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