feat(upm,tool) : make modular tool in into its own window

[arthur740212]

This is a PR for the modular UPM build tool.
This version is made with the Editor Windows changes on version 3.1.0
And instead of applying it on top of the existing upm creation window, it has own window such that no conflicts will occur.
Also to have flexibility during this transition phase

[paulhazen]

There are a few concerns I have about this PR:

Overlap with Create Package Window

I'm concerned this PR could complicate our support matrix. Introducing a new way to create modular packages might lead to discrepancies in package functionality between the CreatePackageWindow and the new modular method, potentially introducing bugs. For instance, packages created on different platforms through different tools could behave inconsistently.

Additionally, updating package descriptions would require changes across multiple JSON files if new files are added to the plugin source. However, these issues could be mitigated by modifying the existing CreatePackageWindow to include an expandable section for platform selection, ensuring uniformity in package creation code.

Clarity around use cases

I need further clarification on when and why users might limit platform support for plugins. For example, if a package is created for Windows and later needs iOS support, this could increase our support tasks significantly. Despite potential file size benefits, it seems deploying games only includes necessary binaries for the chosen platform, so what's the added value of this modular approach?

Changes to UnityPackageCreationUtility

Regarding the changes to make certain methods public in the utility, I believe this could bypass important common tasks handled in the CreatePackage function. It might be more prudent to refactor CreatePackage to incorporate desired flexibility rather than altering method access.

Sorry for being so long-winded 😆

[paulhazen]

This function can (and I think should) be removed - its functionality was put into a FileInfoExtensions class. You can find it at Assets/Plugins/Source/Core/Utility/Extensions/FileInfoExtensions.cs. Once you have that class included via a using statement that includes it, all you need to do is use it:

FileInfo fileOne = new FileInfo(path1);
FileInfo fileTwo = new FileInfo(path2);

if (fileOne.AreContentsSemanticallyEqual(fileTwo))
{
    Debug.Log("The contents of the files are semantically identical.");
}
else
{
    Debug.Log("The contents of the files are _not_ semantically identical.");
}

[andrew-hirata-playeveryware]

I feel like this feature might be a good candidate for our internal new feature runbook.