Listing all groups for a user?

### Description

I have had terrible luck searching for any way to do this with the Az module. Plenty of help for the AzureAD module, but I understand that's essentially dead and I don't want to touch it for all the dire warnings found in Microsoft's documentation. Unclean!

I don't see a command that would provide this data at all other than iterating every single group in the directory and looking for the user in each. That certainly can't be the right way. Can someone point me to the proper command in this module to do this? Surely there must be one, considering how close we are to the end of the AzureAD module's life!

### Script or Debug output

```PowerShell
N/A
```

### Environment data

```PowerShell
Name Value
---- -----
PSVersion 7.2.4
PSEdition Core
GitCommitId 7.2.4
OS Microsoft Windows 10.0.19044
Platform Win32NT
PSCompatibleVersions {1.0, 2.0, 3.0, 4.0…}
PSRemotingProtocolVersion 2.3
SerializationVersion 1.1.0.1
WSManStackVersion 3.0
```

### Module versions

```PowerShell
ModuleType Version Name
---------- ------- ----
Script 2.8.0 Az.Accounts
Script 6.0.0 Az.Resources
```

### Error output

```PowerShell
N/A
```

Start by reviewing the Az.Resources module and its available user and group-membership commands, using the reported PowerShell 7.2.4 and Az.Resources 6.0.0 environment as context. Compare the result with the AzureAD migration guidance; done means identifying and documenting the supported way to list a user's groups, or confirming that the module lacks one.

Written by the indexing model from the issue text.