Add shadowColor and surfaceTintColor to Dialog and DialogTheme

[darrenaustin]

Internal: b/238831308

Currently there is no way to configure the shadow color or surface tint color for Dialogs. We should add these properties to the Dialog constructors as well as the DialogTheme and update the defaults for M3 to set these appropriately.

[rydmike]

Thanks, this will certainly help with all the Dialogs currently getting no elevation when opting in on M3, which happens due to Material's new default behaviour in M3, as mentioned and demonstrated here #107190.

There will still be a lot of Material using Flutter SDK widgets left after this is fixed, that are still affected by the new default Material elevation behaviour when opting in on M3.

Plus the needed extra effort to migrate custom composed widgets using Material, to be able opt in on M3 will remain as well.

[github-actions]

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[darrenaustin]

The original PR had to be reverted, so reopening this. It should be fixed with #110624.