What issue does this PR address?
Refactor The use of ClaimLite and ClaimsRecord into a single type. I decided to use the name 'ClaimsRecord' because it was already part of the public contract (it's protected but still it's part of the signature of the DefaultUserService)

TargetFrameworks vs TargetFramework

There also turned out to be some compile issues. Hence, this PR also adds the
net9.0 to the samples folder. (note ONLY to the samples folder).

The reasoning for this is:
Aspire needs a single target framework
(until this is resolved: dotnet/aspire#2962)

When you add <TargetFrameworks>net9.0</TargetFrameworks> then aspire thinks there are more than
one framework. But this causes a problem for the Directory.Packages.props file.

In the Directory.Packages.props where we check for $(TargetFramework) == 'net9.0',
which is ONLY set if you use <TargetFrameworks>net9.0</TargetFrameworks> in the csproj file, not
if you set <TargetFramework>. 

Now normally it's not recommended to set both, however, since this is only for samples, AND
we do need this check, we're setting it here as well. 

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