feat: Add `ContentDialog` elevation on WASM & Android, partially on iOS

[MartinZikmund]

GitHub Issue (If applicable): part of #7021

PR Type

What kind of change does this PR introduce?

• Feature

What is the current behavior?

No shadow.

What is the new behavior?

Shadow working on WASM and Android. On iOS only without corner radius (not sure why - maybe @carldebilly would know?).

PR Checklist

Please check if your PR fulfills the following requirements:

• [ ] Docs have been added/updated which fit documentation template (for bug fixes / features)
• [ ] Unit Tests and/or UI Tests for the changes have been added (for bug fixes / features) (if applicable)
• [x] Validated PR Screenshots Compare Test Run results.
• [x] Contains NO breaking changes
• [x] Associated with an issue (GitHub or internal) and uses the automatic close keywords.
• [x] Commits must be following the Conventional Commits specification.

Other information

Internal Issue (If applicable):

[gitpod-io[bot]]

[jeromelaban]

/azp run

[azure-pipelines[bot]]

Azure Pipelines successfully started running 1 pipeline(s).

[jeromelaban]

Are we able to validate the presence of the elevation via a screenshot color peeking ?

[jeromelaban]

Looks like SetElevation is missing somewhere.

[agneszitte]

/azp run

[azure-pipelines[bot]]

Azure Pipelines successfully started running 2 pipeline(s).

[agneszitte]

@MartinZikmund there is some conflicts that needs to be resolved ;)