Pass active tab to tabs partial view

[trichoplax]

Main change

This passes the name of the active tab to the partial view app/views/users/_tabs.html.erb to remove the need for each tab to check the current page to decide if it should show as active.

This is a fairly trivial change at this stage, but will become more useful in #2063 where a Moderator Tools tab will be introduced that needs to show as active for 11 different URLs.

Additional changes

This pull request also includes other changes triggered by working on the tabs:

• The Subscriptions page (for emails) had the tabs along the top, but wasn't listed among them, resulting in an odd look with no active tab. I've added a tab for Subscriptions to fix this, and removed the right hand panel for consistency with the other tabs.
• The tabs now take up enough horizontal space that reading through them takes a while and they run on to two lines on smaller screens or at higher zoom levels. I've reduced their width with the following changes:
  • Removed the icon from the "Profile" tab.
  • Changed "Vote Summary" to "Votes".
  • Changed "Notifications" to "Inbox".
  • Changed "Subscriptions" to "Email".
  • Changed "All Communities" to "Network".

Let me know if you'd prefer the Subscriptions page to be an independent page with no tabs along the top, or if you'd prefer to avoid any of these width reducing changes.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 80.93%. Comparing base (1aa4379) to head (a32fc40).

Additional details and impacted files

Components	Coverage Δ
controllers	76.73% <100.00%> (+<0.01%)	⬆️
helpers	85.47% <ø> (ø)
jobs	77.43% <ø> (ø)
models	93.14% <ø> (ø)
tasks	61.11% <ø> (ø)

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[cellio]

LGTM. Ran through the tabs at both desktop and phone sizes.