[Test] Add UI testing

[grgprarup]

• [x] setup UI test #28

• [ ] Test scenarios for UI Test

  1. Opening a markdown file and viewing in the presentation viewer
     • [x] check if markdown is rendered properly according to their tags (eg.: #-> <h1>) https://github.com/JankariTech/web-app-presentation-viewer/pull/49 (Not required in e2e)
     • [ ] check for the content of the slide
     • [ ] number of slides is correct
  2. Test slide change
     • [ ] with button on UI
     • [ ] with keyboard
  3. Test coverage for:
     • [ ] https://github.com/JankariTech/web-app-presentation-viewer/issues/11
     • [ ] https://github.com/JankariTech/web-app-presentation-viewer/issues/13

• [x] UI tests in CI (https://github.com/JankariTech/web-app-presentation-viewer/pull/51)

[anon-pradip]

Test scenarios for UI Test

1. Opening a markdown file and viewing in the presentation viewer
   • [ ] check if markdown is rendered properly according to their tags (eg.: #-> <h1>)
   • [ ] check for the content of the slide
   • [ ] number of slides is correct
2. Test slide change
   • [ ] with button on UI
   • [ ] with keyboard
3. Test coverage for:
   • [ ] https://github.com/JankariTech/web-app-presentation-viewer/issues/11
   • [ ] https://github.com/JankariTech/web-app-presentation-viewer/issues/13