Add github actions

[wiruzx]

• Added script for running tests for Chatto, ChattoAdditions and ChattoApp

Usage:

# to run Chatto tests:
./scripts/test.sh chatto
# to run ChattoAdditions tests:
./scripts/test.sh additions
# to run ChattoApp tests
./scripts/test.sh app

Please note that you should run this script from the root folder of the repo

• Replaced Travis-CI integration with Github Actions
  It runs tests much faster and has native integration with github.

[codecov-commenter]

Codecov Report

Merging #678 into master will decrease coverage by 0.11%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master     #678      +/-   ##
==========================================
- Coverage   44.77%   44.65%   -0.12%     
==========================================
  Files          98       98              
  Lines        5119     5119              
==========================================
- Hits         2292     2286       -6     
- Misses       2827     2833       +6     

Impacted Files	Coverage Δ
...Chat Items/TextMessages/Views/TextBubbleView.swift	27.51% <0.00%> (-3.18%)	⬇️

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