Explore the use of .NET Generic Host for Bicep CLI

Created from this comment:

> These are out of the scope this PR and can be addressed later:
>
> - It looks like we don’t currently have e2e tests for the snapshot command.
> - It may be worth exploring the use of [.NET Generic Host](https://learn.microsoft.com/en-us/dotnet/core/extensions/generic-host?tabs=appbuilder).

_Originally posted by @shenglol in https://github.com/Azure/bicep/issues/19312#issuecomment-4512547301_

Start with the .NET Generic Host documentation linked in this issue and the originating discussion in issue #19312. Identify the Bicep CLI entry points involved and evaluate whether adopting Generic Host is appropriate; done means a clear recommendation and implementation scope.

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