Add templates for source with just version numbers

[Micket]

Adding templates for the common %(version)s.tar.gz and v%(version)s.tar.gz sources.

E.g.

1. VERSION_TAR_GZ
2. VVERSION_ZIP

I didn't know a better option but to append an extra V for the second option.

I haven't tested anything yet, throwing it out there to gauge the response first.

[Micket]

ping @Flamefire who i think has explicitly requested this before.

[Flamefire]

Thanks for that

One alternative to VVERSION_<ext> could be V_VERSION_<ext> which makes it easier to see the "v" while being a single char longer

And maybe we should keep the SOURCE_ suffix at least for discoverability among the other templates

[Flamefire]

No need to make this 2 operations which might slow down EB startup even further.

Suggested change

	})
	TEMPLATE_CONSTANTS.update({

Played around with the prior code how to do this with a single update call and dict comprehension (fastest in CPython) but not sure if people find this easier to read ;-)

TEMPLATE_CONSTANTS.update({
    key: value
    for ext in EXTENSIONS
    for key, value in (
        (
            f"SOURCE_{ext.replace('.', '_').upper()}",
            (f"%(name)s-%(version)s.{ext}", f"Source .{ext} bundle"),
        ),
        (
            f"SOURCELOWER_{ext.replace('.', '_').upper()}",
            (f"%(namelower)s-%(version)s.{ext}", f"Source .{ext} bundle with lowercase name"),
        ),
    )
})