Context animation functions could use `impl Into<Id>` instead of just `Id`

Many functions that require an `Id` specify the parameter as `impl Into`. This means for 99% of cases you can just use an `&'static str` (which is convenient).

These 3 functions require something like `"my_id".into()` which is slightly less ergonomic.

* [animate_bool](https://github.com/emilk/egui/blob/0.27.2/crates/egui/src/context.rs#L2412)
* [animate_bool_with_time](https://github.com/emilk/egui/blob/0.27.2/crates/egui/src/context.rs#L2419)
* [animate_value_with_time](https://github.com/emilk/egui/blob/0.27.2/crates/egui/src/context.rs#L2440)

These are the only functions I've run into that have this quirk while working with `egui`, but there may be more as well. At a minimum, I'd like to submit a PR to make these ones more convenient to use.

Start in crates/egui/src/context.rs at animate_bool, animate_bool_with_time, and animate_value_with_time, using the linked locations as entry points. Check the surrounding function signatures and existing callers, then verify that the three functions accept the same convenient Id inputs as the other context animation functions.

Written by the indexing model from the issue text.