Automatically Inject MonoGame Version In Documentation

[AristurtleDev]

Description

This PR adds a new feature to the documentation where using the tokens {{mgVersion}} or {{mgDevelopVersion}} will automatically inject the version configured in the new mgversion.json file.

The changes include:

• Creation of mgversion.json containing mgVersion and mgDevelopVersion.
• Updates to docfx.json and ci.docfx.json to include mgversion.json via globalMetadataFiles.
• Updates to conceptual.extension.js to replace all occurrences of {{mgVersion}} and {{mgDevelopVersion}} in the Markdown content with the configured values.
• Updated Markdown documents to replace hardcoded version numbers with the new tokens.

This ensures that the documentation always reflects the correct MonoGame version and makes it easy to update the versions in one place.

Note:

@SimonDarksideJ: There are a couple of places where I was unsure if the documentation should always reflect the current version number of if it should remain hard coded. Specifically in the migration document here

docs.monogame.github.io/articles/migration/migrate_38.md

Lines 136 to 139 in bbca6d5

	## Remove `RestoreDotNetTools` section from csproj
	From `3.8.4.1` and above, the `RestoreDotNetTools` section is no longer required in client project `csproj` files, as the processing is now handled within the MonoGame deliverables.

docs.monogame.github.io/articles/migration/migrate_38.md

Lines 155 to 159 in bbca6d5

	## iOS/iPadOS, and Android Considerations
	DotNet 9 is MANDATORY for iOS and Android due to platform requirements, as well as the following configurations:
	- MonoGame 3.8.4.1 is **REQUIRED** to comply with the Google Policies on 16kb pages and other affordances.

Related Issues

• Closes Inconsistent MonoGame Versions in Documentation #208

[SimonDarksideJ]

While in principle, I agree with this approach to simplify versioning in the documentation. However, there are a few areas where this has implemented which is not fit for purpose, such as:

• Where something changed FROM a specific version, this should not be updated because it was a fixed point in time, such as .NET 9 FROM 3.8.4.1

Please review and update as appropriate.