--verbosity does not accept capitalized values

I'm using [Nuke](https://nuke.build/) to implement various pipelines.

I added dotnet format (see https://github.com/nuke-build/nuke/pull/1032), which is already released with the latest version.

Nuke handle verbosity for `dotnet` with the enum `DotNetVerbosity`.
```csharp
public partial class DotNetVerbosity : Enumeration
{
public static DotNetVerbosity Quiet = (DotNetVerbosity) "Quiet";
public static DotNetVerbosity Minimal = (DotNetVerbosity) "Minimal";
public static DotNetVerbosity Normal = (DotNetVerbosity) "Normal";
public static DotNetVerbosity Detailed = (DotNetVerbosity) "Detailed";
public static DotNetVerbosity Diagnostic = (DotNetVerbosity) "Diagnostic";
public static implicit operator DotNetVerbosity(string value)
{
return new DotNetVerbosity { Value = value };
}
}
```

This enum is now also used for dotnet format. All dotnet commands which I use (`clean`, `restore`, `compile`, `pack`) can handle verbosity with capitalized value except `format`.

Console Output:
```
C:\projects\format_test>dotnet clean FormatTest.sln --verbosity Quiet
MSBuild version 17.4.0+18d5aef85 for .NET

C:\projects\format_test>dotnet restore FormatTest.sln --verbosity Quiet

C:\projects\format_test>dotnet build FormatTest.sln --verbosity Quiet
MSBuild version 17.4.0+18d5aef85 for .NET

Build succeeded.
0 Warning(s)
0 Error(s)

Time Elapsed 00:00:01.46

C:\projects\format_test>dotnet pack FormatTest.sln --verbosity Quiet
MSBuild version 17.4.0+18d5aef85 for .NET

C:\projects\format_test>dotnet format FormatTest.sln --verbosity Quiet --verify-no-changes
Argument 'Quiet' not recognized. Must be one of:
'q'
'quiet'
'm'
'minimal'
'n'
'normal'
'd'
'detailed'
'diag'
'diagnostic'

Description:
Formats code to match editorconfig settings.

Usage:
dotnet-format [] [command] [options]

Arguments:
The project or solution file to operate on. If a file is not specified, the command will search the current directory for one. [default: C:\projects\format_test\]

Options:
--diagnostics A space separated list of diagnostic ids to use as a filter when fixing code style or 3rd party issues. []
--exclude-diagnostics A space separated list of diagnostic ids to ignore when fixing code style or 3rd party issues. []
--severity The severity of diagnostics to fix. Allowed values are info, warn, and error.
--no-restore Doesn't execute an implicit restore before formatting.
--verify-no-changes Verify no formatting changes would be performed. Terminates with a non-zero exit code if any files would have been formatted.
--include A list of relative file or folder paths to include in formatting. All files are formatted if empty. []
--exclude A list of relative file or folder paths to exclude from formatting. []
--include-generated Format files generated by the SDK.
-v, --verbosity Set the verbosity level. Allowed values are q[uiet], m[inimal], n[ormal], d[etailed], and diag[nostic]
--binarylog Log all project or solution load information to a binary log file.
--report Accepts a file path which if provided will produce a json report in the given directory.
--version Show version information
-?, -h, --help Show help and usage information

Commands:
whitespace Run whitespace formatting. [default: C:\projects\format_test\]
style Run code style analyzers and apply fixes. [default: C:\projects\format_test\]
analyzers Run 3rd party analyzers and apply fixes. [default: C:\projects\format_test\]

C:\projects\format_test>
```

Would be really useful when `dotnet format` supports also capitalized verbosity values like `Quiet`, `Minimal`, ... and it would be consistent to other dotnet commands.