Add CI testing for all feature flag combinations and fix all reported errors

[Shute052]

Objective

Make sure we thoroughly test all feature-related code and updates.

Solution

Cover all combinations of features our crate offers when running CI tests for clippy, doc-check, doc-test, test, and compile-check.

For instance, given the current existence of four features: asset, ui, block_ui_interactions, and egui, the new CI testing will include scenarios like:

• Testing with --no-default-features
• Testing with --all-features
• Testing with individual features enabled:
  • --features=asset
  • --features=ui
  • --features=block_ui_interactions
  • --features=egui
• Testing with various combinations of features enabled:
  • --features=asset,ui
  • --features=asset,block_ui_interactions
  • --features=asset,egui
  • --features=ui,block_ui_interactions
  • --features=ui,egui
  • --features=block_ui_interactions,egui
  • --features=asset,ui,block_ui_interactions
  • --features=asset,ui,egui
  • --features=asset,block_ui_interactions,egui
  • --features=ui,block_ui_interactions,egui

This ensures we catch any regressions or issues related to the features.

TODO

• fix all reported errors (without those reporting from doc-check)

Changelog

• Add new CI testing for all feature flag combinations

[Shute052]

When running doc-check with scenarios excluding the ui feature, the new testing reports the following issues:

error: unresolved link to `crate::systems::update_action_state_from_interaction`
  --> src/action_driver.rs:20:58
   |
20 | /// By default, [`update_action_state_from_interaction`](crate::systems::update_action_state_from_interaction) uses this component
   |                                                          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ no item named `update_action_state_from_interaction` in module `systems`
   |
   = note: `-D rustdoc::broken-intra-doc-links` implied by `-D warnings`
   = help: to override `-D warnings` add `#[allow(rustdoc::broken_intra_doc_links)]`

error: unresolved link to `crate::systems::update_action_state_from_interaction`
  --> src/action_driver.rs:55:71
   |
55 | ...n`](crate::systems::update_action_state_from_interaction) for an example of how this is done.
   |        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ no item named `update_action_state_from_interaction` in module `systems`

error: unresolved link to `Interaction`
   --> src/input_mocking.rs:[119](https://github.com/Leafwing-Studios/leafwing-input-manager/actions/runs/7970380465/job/21757867601?pr=475#step:6:120):26
    |
119 |     /// as well as any [`Interaction`] components and all input [`Events`].
    |                          ^^^^^^^^^^^ no item named `Interaction` in scope
    |
    = help: to escape `[` and `]` characters, add '\' before them like `\[` or `\]`

error: unresolved link to `crate::systems::update_action_state_from_interaction`
  --> src/plugin.rs:52:48
   |
52 | /// - [`update_action_state_from_interaction`](crate::systems::update_action_state_from_interaction), for triggering actions from buttons
   |                                                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ no item named `update_action_state_from_interaction` in module `systems`

error: unresolved link to `bevy::ui::Interaction`
  --> src/plugin.rs:53:[122](https://github.com/Leafwing-Studios/leafwing-input-manager/actions/runs/7970380465/job/21757867601?pr=475#step:6:123)
   |
53 | ...component based on an [`Interaction`](bevy::ui::Interaction) component
   |                                          ^^^^^^^^^^^^^^^^^^^^^ no item named `ui` in module `bevy`

[Shute052]

All these unresolved links occur because they are excluded when the ui feature is disabled.
Alternatively, we could only run doc-check with the --all-features option to ignore those errors.

[alice-i-cecile]

Let's run doc check only with all features. I care much more about the links working on docs.rs than locally.

[Shute052]

In that case, this PR shouldn't have any further actions needed, at least for now.

[Shute052]

To validate everything's working as expected, try removing some of the code that depends on feature flags. This should trigger the errors we're looking for.

For example, parts like this mentioned

/// Remove this cfg in the 'src/input_map.rs'
#[cfg(feature = "asset")]
use bevy::asset::Asset;