feat(input): add styles for round shape to ionic theme (#29329)

Issue number: Internal

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## What is the new behavior?
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this PR. -->

Added styles for `shape="round"`, including:
- Increased border radius
- Increased padding when additionally using outline fill and large size
- Horizontal padding also applied to label when using outline fill

I also changed the `$ionic-border-radius-rounded-full` design token from
100% to 999px. `border-radius: 100%` is pretty obviously incorrect for
most browsers (screenshot taken in Chrome):

![image](https://github.com/ionic-team/ionic-framework/assets/90629384/5dc47a65-0446-4e39-9ce3-1c749b6329e7)

## Does this introduce a breaking change?

- [ ] Yes
- [x] No

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## Other information

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screenshots of how the component looks before and after the change. -->

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Co-authored-by: ionitron <hi@ionicframework.com>

core/src/components/input/input.ionic.scss

@@ -21,6 +21,13 @@
   min-height: 48px;
 }
 
+// Ionic Input Shapes
+// --------------------------------------------------
+
+:host(.input-shape-round) {
+  --border-radius: #{$ionic-border-radius-rounded-full};
+}
+
 // Input Bottom Content
 // ----------------------------------------------------------------