Clean up login/token/user-related things

[imnasnainaec]

Sequel to #3920

Prequel to #3877

Changes:

• InviteController: method ValidateToken -> ValidateInviteToken (to avoid ambiguity in OpenAPI with other tokens)
• PasswordResetService:
  • param EmailOrUsername -> emailOrUsername
  • remove unnecessary method ExpirePasswordReset
  • email title "Combine ..." -> "The Combine ..."
• InvalidLink component: add prop for optional body text
• ProjectInvite component: remove extraneous executions of validateLink
• SignUp component: prop returnToEmailInvite -> onSignup (for more general use)
• UserSettings component: set email state from normalization of new emailPunycode state (to only normalize in one place)
• userUtilities:
  • created from two utilities functions and one UserSettings function
  • enqueueSnackbar -> toast.success

---

This change is 

[codecov]

Codecov Report

❌ Patch coverage is 72.00000% with 7 lines in your changes missing coverage. Please review.
✅ Project coverage is 73.76%. Comparing base (3078992) to head (100ef0f).
⚠️ Report is 4 commits behind head on master.

Files with missing lines	Patch %	Lines
src/components/InvalidLink/index.tsx	0.00%	5 Missing ⚠️
src/components/Login/ProjectInvite.tsx	0.00%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #3938      +/-   ##
==========================================
- Coverage   73.78%   73.76%   -0.02%     
==========================================
  Files         289      290       +1     
  Lines       10565    10563       -2     
  Branches     1328     1328              
==========================================
- Hits         7795     7792       -3     
- Misses       2386     2387       +1     
  Partials      384      384              

Flag	Coverage Δ
backend	85.40% <100.00%> (-0.01%)	⬇️
frontend	65.06% <66.66%> (-0.02%)	⬇️

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[jasonleenaylor]

@jasonleenaylor reviewed 21 of 21 files at r1, 2 of 2 files at r2, 3 of 3 files at r3, all commit messages.
Reviewable status: complete! all files reviewed, all discussions resolved (waiting on @imnasnainaec)