Change verbosity levels to the recommended ones by System.CommandLine

**Is your feature request related to a problem? Please describe.**
The verbosity levels are p.t. linked to the default values in Microsoft.Extensions.Logging (see https://erikbra.github.io/grate/configuration-options/)

However, the documentation for System.CommandLine recommends different verbosity levels, in line with other command-line tools, like e.g. `dotnet`, and `msbuild`. I think those are more intuitive too. See https://docs.microsoft.com/en-us/dotnet/standard/commandline/syntax#the---verbosity-option

**Describe the solution you'd like**
We should use the following verbosity levels:

* Q[uiet]
* M[inimal]
* N[ormal]
* D[etailed]
* Diag[nostic]

Instead of the current ones, which are:

* Critical
* Debug
* Error
* Information
* None
* Trace
* Warning

The mapping to the current values, which are the ones used throughout in code, should be done on parsing the command line, so that we don't change a lot of code for this.The following logic should be used when mapping the verbosity levels to minimum log levels:

* Quiet -> Error
* Minimal -> Warning
* Normal -> Information
* Detailed -> Debug
* Diag -> Trace

For backwards compatibility, we should also accept the current values, but mark them as obsolete (maybe wait a couple of releases before making them obsolete)