This:

* replaces all instances of kdesrc-build everywhere in Develop to kde-builder
* replaces links like kdesrc-build-setup to kde-builder-setup
* promotes kde-builder by the sheer fact of displaying how much simpler it is to use
* maintains aliases for all kdesrc-build pages
* follows https://develop.kde.org/docs/contribute/style/#migration : kdesrc-build users will still know how to find the required docs and the differences between commands/syntax where relevant
* the main pages have top alerts mentioning that kdesrc-build is now unsupported
* the main pages don't clog the actual tutorial content because they hide the kdesrc-build behind a collapsible
* incorportates "How to build Qt?" since with kde-builder it's easy
* provides a nice table for the user to choose the right method for them
* provides a status on how up-to-date the IDE guides are
* adds a few links to kde-builder-setup in other places that already needed them
* adds emojis to some alerts about kde-builder/kdesrc-build to make them friendlier
* makes a few of the outdated IDE guides slightly more readable
* mentions how the user can contact the team to fix the outdated guides

This affects the following tutorials:

* kdesrc-build
* manual CMake
* distrobox
* IDE
* Kirigami
* KXmlGui
* Appium
* KMines

Closes #193