[DDW-490] Use a small icon for the window and a large icon for the desktop

[cleverca22]

This PR fixes window icon issues on Linux which were a result of using high quality icon which was poorly downscaled in order to be used as a small window title bar icon.

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Review Checklist:

Basics

• PR is updated to the most recent version of target branch (and there are no conflicts)
• PR has good description that summarizes all changes and shows some screenshots or animated GIFs of important UI changes
• CHANGELOG entry has been added and is linked to the correct PR on GitHub
• Automated tests: All acceptance tests are passing (yarn run test)
• Manual tests (minimum tests should cover newly added feature/fix): App works correctly in development build (yarn run dev)
• Manual tests (minimum tests should cover newly added feature/fix): App works correctly in production build (yarn run package / CI builds)
• There are no flow errors or warnings (yarn run flow:test)
• There are no lint errors or warnings (yarn run lint)
• Text changes are proofread and approved (Jane Wild)
• There are no missing translations (running yarn run manage:translations produces no changes)
• UI changes look good in all themes (Alexander Rukin)
• Storybook works and no stories are broken (yarn run storybook)
• In case of dependency changes yarn.lock file is updated

Code Quality

• Important parts of the code are properly documented and commented
• Code is properly typed with flow
• React components are split-up enough to avoid unnecessary re-rendering
• Any code that only works in Electron is neatly separated from components

Testing

• New feature / change is covered by acceptance tests
• All existing acceptance tests are still up-to-date
• New feature / change is covered by Daedalus Testing scenario
• All existing Daedalus Testing scenarios are still up-to-date

After Review:

• Merge PR
• Delete source branch
• Move ticket to done on the Youtrack board

[nikolaglumac]

@amias-iohk can you please test the Linux build once it is ready? Thanks!

[amias-iohk]

checked on ubuntu 18.10 with the gnome-shell desktop (this isn't an issue with unity) and the icons are now much better quality, screen shot from a 4k desktop. well done everyone :)

[nikolaglumac]

@amias-iohk what about the desktop icon? Is that one looking well too?

[amias-iohk]

they seem a little smaller , mainnet is old style , staging is new style