Auto merge of #17775 - michael-p:rename-stylearc-to-servo-arc, r=emilio

Replace all uses of the style::stylearc alias with servo_arc.

The `stylearc` alias is left there temporarilly and will be removed completely in a later commit/PR where also `components/style/gecko/generated/structs_{debug|release}.rs` are re-generated (they still use the old alias).

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- [X] `./mach build -d` does not report any errors
- [X] `./mach test-tidy` does not report any errors
- [X] These changes fix #17768  (github issue number if applicable).

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- [ ] There are tests for these changes OR
- [X] These changes do not require tests because no new features / only refactoring

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components/style/animation.rs

@@ -16,8 +16,8 @@ use properties::longhands::animation_direction::computed_value::single_value::T
 use properties::longhands::animation_iteration_count::single_value::computed_value::T as AnimationIterationCount;
 use properties::longhands::animation_play_state::computed_value::single_value::T as AnimationPlayState;
 use rule_tree::CascadeLevel;
+use servo_arc::Arc;
 use std::sync::mpsc::Sender;
-use stylearc::Arc;
 use stylesheets::keyframes_rule::{KeyframesStep, KeyframesStepValue};
 use timer::Timer;
 use values::computed::Time;