Deduplicate verification diagnostic reporting between CLI and server

[keyboardDrummer]

Description

Mature the IPhase concept by bigger use of it in more locations. In particular, it is now used for verification and verification coverage diagnostics.

Specific changes:

• Let Compilation (the back-end) report verification diagnostics, instead of the two front-ends IdeState.HandleBoogieUpdate (IDE) and VerifyCommand.ReportVerificationDiagnostics (CLI), reducing duplication.
• Let Compilation call WarnAboutSuspiciousDependenciesForScope instead of IdeState.HandleBoogieUpdate (IDE) and VerifyCommand.LogVerificationResults (CLI), reducing duplication.
• IDE only: store phase state in a tree, to enable quickly finding and removing nodes from the tree.
• CLI only: sort diagnostics using phases

How has this been tested?

• This is a refactoring, no additional tests are needed

By submitting this pull request, I confirm that my contribution is made under the terms of the MIT license.