Changes how dependency options are handled and moves them out of
`CMakeLists.txt`.
Major changes:
1. The static default now takes `TARGET_SUPPORTS_SHARED_LIBS` into account
2. The `DIST` setting no longer affects the static default.
3. The static option is now visible for system dependencies as well.
(it was previously hidden by `cmake_dependent_option`).
4. The auto-detection mechanism for `libfmt` and `SDL_image` only
applies if the setting has not been set.
5. SDL2 on Android is now also linked statically,
resulting in a 1.1 MiB smaller APK.
When using non-system dependencies, the default should always be static,
as there are 2 main use cases for these:
1. Dependencies that we must currently vendor because our forks have
significant changes that are not yet merged/released upstream.
2. Platforms that have no system packages, such as Android and iOS.
In both cases, static linking is the most appropriate default.
Gleb Mazovetskiy
Dennis Duda
Sergey Semushin
galaxyhaxz
aperturesecurity
galaxyhaxz
Leonard