Describe the bug

Context::load_texture acquires a read lock to the context's InputState, which is unexpected. I discovered this by accidentally holding a handle from Context::input_mut for longer than necessary, and calling load_texture with it held. At time of writing, the lock is acquired here: https://github.com/emilk/egui/blob/master/crates/egui/src/context.rs#L755

To Reproduce
Steps to reproduce the behavior:

1. Call Context::input_mut in your UI code to query user inputs.
2. Later (perhaps in response to user action consumed with InputState::consume_key), call Context::load_texture, before the MappedRwLockWriteGuard from input_mut is dropped.

I can write a minimal working example later if needed, but hopefully this is clear enough.

Expected behavior
Texture loading code would not interact with InputState.

Screenshots
N/A

Desktop (please complete the following information):
This isn't OS specific.

Additional context
It seems strange that loading a texture would have anything to do with the user input, but this could reasonably be solved by documenting this behavior on Context::load_texture. It's easy enough to work around (just drop the lock guard earlier), but it's tricky to realize what's happening without debugging egui code.