Changelog for metadata and better validation

[MartinM85]

Is there any chance to generate a changelog when metadata are changed?

As a developer I've no idea what exactly was added or removed.

The only way is to check pull requests for SDKs, but pull requests have changes in thousands of files

https://github.com/microsoftgraph/msgraph-sdk-dotnet/pull/2521/files
https://github.com/microsoftgraph/msgraph-sdk-dotnet/pull/2530/files

The changelog can help me decide whether to update to a new version or not.

The most frequent changes are in the comments, so changes in the comments do not have to be mentioned in the changelog.

The comments are the things where the most mistakes are visible at first glance. Obviously, no one is checking the changes.

Updating the .NET SDK takes seconds, but in case of PowerShell SDK, it takes (tens of) minutes

[MartinM85]

If it's not related to this repo, I will probably close it.