Implemented the option to insert a photo via an external url

[RafaelSousaLima]

Variable was created in AngularEditorConfig that says which way the user will insert the photo. If false, it will follow the existing flow, if true, it will open a window for the user to insert the url of the image they want to insert.

[codecov]

Codecov Report

Merging #369 (daf5ef7) into master (e751169) will decrease coverage by 0.15%.
The diff coverage is 0.00%.

@@            Coverage Diff             @@
##           master     #369      +/-   ##
==========================================
- Coverage   18.81%   18.65%   -0.16%     
==========================================
  Files           7        7              
  Lines         473      477       +4     
  Branches      103      104       +1     
==========================================
  Hits           89       89              
- Misses        372      378       +6     
+ Partials       12       10       -2     

Impacted Files	Coverage Δ
...editor/src/lib/angular-editor-toolbar.component.ts	16.40% <0.00%> (-0.53%)	⬇️
projects/angular-editor/src/lib/config.ts	100.00% <ø> (ø)
...angular-editor/src/lib/angular-editor.component.ts	13.93% <0.00%> (ø)

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