Sensor API: allow specifying update rate

[slime73]

Sensor update rates can affect battery life on phones, and different apps/games might have different ideal sensor update rates depending on what they do with the data and what their target framerate is.

iOS and Android both support setting an update rate, I'm not familiar with other platforms though. On iOS at least it can be set per sensor type. There's a FIXME comment in the Android sensor code which suggests adding a hint for this feature, but since SDL3 is coming up I think it should be integrated into the sensor APIs directly instead (either in the Open functions or as its own API?)

Related: https://github.com/libsdl-org/SDL/issues/3606

[slouken]

I'm bumping this to 3.x. We can easily add functions to query sensor rates and set desired sensor rates at any point in the future. If this is important for you, please feel free to submit a PR anytime.