add rectangle support (rebase version)

[sebholstein]

closes #1206

[sebholstein]

resolved conflicts, ported tests to Jest

[codecov]

Codecov Report

Merging #1450 into master will increase coverage by 2.1%.
The diff coverage is 48.81%.

@@            Coverage Diff            @@
##           master    #1450     +/-   ##
=========================================
+ Coverage   26.34%   28.45%   +2.1%     
=========================================
  Files          28       30      +2     
  Lines        1226     1353    +127     
  Branches      159      182     +23     
=========================================
+ Hits          323      385     +62     
- Misses        901      966     +65     
  Partials        2        2

Impacted Files	Coverage Δ
packages/core/services/google-maps-types.ts	0% <ø> (ø)	⬆️
packages/core/directives/map.ts	0% <0%> (ø)	⬆️
packages/core/core.module.ts	0% <0%> (ø)	⬆️
packages/core/services/google-maps-api-wrapper.ts	35.13% <25%> (-0.58%)	⬇️
packages/core/directives/rectangle.ts	44.82% <44.82%> (ø)
...ckages/core/services/managers/rectangle-manager.ts	64.7% <64.7%> (ø)

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