feat(progress-bar): add styling for the ionic theme (#30185)

Issue number: internal

---------

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## What is the current behavior?
ion-progress-bar does not currently have any custom styling for the
ionic theme.

## What is the new behavior?
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this PR. -->
According to the design, the following styling changes were made:
- Added a new shape prop which controls the shape of the progress bar
- Changed the color of the unfilled part of the progress bar and the bar
height to design token values
- Adding a new testing page and screenshot tests

## 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. -->

packages/vue/src/proxies.ts

@@ -619,7 +619,8 @@ export const IonProgressBar = /*@__PURE__*/ defineContainer<JSX.IonProgressBar>(
   'reversed',
   'value',
   'buffer',
-  'color'
+  'color',
+  'shape'
 ]);