Draft: Add Appium test guide

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What does this merge request add?

How to run Appium tests for applications on Linux

Related Issues

Replaces teams/eco/be4foss!79

Screenshot of the result (optional)

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How to test this MR

git clone https://invent.kde.org/documentation/develop-kde-org.git
cd develop-kde-org
git mr <THE NUMBER OF THIS MR>
hugo server

Closes

(If this merge request closes any issue in this repository, use Closes #<mr number> here, for example: Closes #3)