Fork HelpWithCovid and HelpWithBlackEquity from a core HelpWith app

[jamiew]

Now that we're adding theme support, it makes sense to rebrand this app
as simply 'HelpWith' and make the initial data more generic.

Part of that means splitting anything Covid or BlackEquity-related into
their own custom themes and repositories, like the current helpwithblackequity branch

While working with branches is simpler, each app might have their own contributors,
build settings, webhooks etc. We should split the app up into three repositories:

• helpwith
• helpwithcovid (current master branch)
• helpwithblackequity (current helpwithblackequity branch)