Add return type command for class names to language features

[ZachWatkins]

It was suggested in pull request #2263 that I should see if the maintainers want a return type command I made for PHP to be available in the common language files (likely after modifications).

(Edit: Since this issue didn't receive a comment after the last maintainers meeting, I will assume it would be easier to discuss this if I submitted a PR. I will submit 2 separate PRs: (1) for the "returns class" command to be added to ./lang/tags/functions.talon, and (2) for the "returns global class" command to be added to ./lang/tags/functions.talon (since "returns global class" may not be necessary for other languages (see below)). I am hoping this makes it easier to discuss and review the different solutions that would add "returns class <user.text>" to the project. If one or both PRs are declined, then I will submit a third to add the declined change(s) to the PHP language file.)

Here is the code I submitted with recommended corrections:

returns class <user.text>
    formatted = user.formatted_text(text, "PUBLIC_CAMEL_CASE")
    insert(": {formatted}")

returns global class <user.text>:
    formatted = user.formatted_text(text, "PUBLIC_CAMEL_CASE")
    insert(": \\{formatted}")

The code above is fine for PHP, but aren't there languages which do not require camel case for their class names? If so, additional language-specific logic is required and possibly as a user setting as well. Edit: Since ./core/snippets/snippets/classDeclaration.snippet uses PUBLIC_CAMEL_CASE as the only insertion formatter, I will assume it is fine to use for these commands.

Edit:

About the "returns global class" command, other languages may not need this command. PHP uses namespaces for class, interface, function, and constant definitions. Namespaces use the \ character to declare subnamespaces, and a global namespace reference can be made by prefixing it with \. When a namespace is declared, namespace resolution first checks whether proceeding classes and functions are registered in that namespace. Prefixing them with "" explicitly declares they use the global space. Simple example:

<?php
namespace App;
function currentDate(): \DateTime {
    return new \DateTime();
}