feat(avatar): add styles for xlarge size in ionic theme (#29549)

Issue number: internal

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## What is the current behavior?
Avatar does not have styles for the `"xlarge"` size in the ionic theme.

## What is the new behavior?
- Adds the styles for the xlarge size (width, height, padding, font size
and line height)
- Adds e2e test for xlarge size to the existing avatar test for sizes

## Does this introduce a breaking change?

- [ ] Yes
- [x] No

## Other information

[Preview](https://ionic-framework-git-rou-10737-ionic1.vercel.app/src/components/avatar/test/size?ionic:theme=ionic)

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Co-authored-by: Giuliana Silva <108938618+OS-giulianasilva@users.noreply.github.com>