fix(toast): keep icon on the same line as long message in stacked layout (#30923)

Issue number: resolves #30908

---------

## What is the current behavior?
Toast with an icon and long message using a stacked layout will wrap the
message below the icon.

## What is the new behavior?
- Apply `flex: 1` to `.toast-content` regardless of layout, which makes
sure the content does not get wrapped under the icon
- Adds an e2e test for a stacked toast with a long message to
`toast/test/layout`

## Does this introduce a breaking change?
- [ ] Yes
- [x] No

## Other information

- Dev build: `8.7.18-dev.11768592717.14a59d2f`
- Preview:
[Layout](https://ionic-framework-git-fw-7035-ionic1.vercel.app/src/components/toast/test/layout/)

---------

Co-authored-by: Brandy Smith <6577830+brandyscarney@users.noreply.github.com>