Indent rule option to allow spaces after tabs

[JoshuaKGoldberg]

Allows a configurable maximum number of spaces after tabs.

Fixes #1306.

[jkillian]

Feeling a little hesitant on this, let's see what others think before going further. Worst case you can always make this a custom rule if needed in some of your projects

[olegstepura]

IMHO one should make a choice and never mix spaces with tabs.

[ChrisMBarr]

Yeah I agree, I can't see a lot of people needing a rule to enforce tabs only, but also sometime allow a maximum of 3 spaces after that. Perhaps that makes sense for your team, but I cannot think of a good use case for that option.

Typically the choices are "tabs", "spaces", or "I don't care to enable this rule"

[JoshuaKGoldberg]

@ChrisMBarr I've put a defense + use case in the other thread, #1306 (comment)

[jkillian]

I understand where you're coming from @JoshuaKGoldberg, but mixing tabs and spaces doesn't seem like an idea we want to encourage, so I'm going to close this. I never enjoy closing PRs that people have put time and effort into, but in this case it seems like the best course of action.

[JoshuaKGoldberg]

Makes sense, no worries! I appreciate you & the other participants taking the time to think it over and give feedback.

[vhakulinen]

I'll leave my (and probably my colleague's) two cents here and vouch for this opt-in feature. I can really relate to this comment: #1306 (comment) (already mentioned above by @JoshuaKGoldberg). Really useful when you're using tabs for indention but still want to line up arguments or conditions in if statement with the line above (after indention tabs).