check token balance covers first contribution

[danlipert]

Description

This PR checks a users token balance to ensure they have enough tokens to cover their grant contribution, or at least the first in a series of recurring contributions

Refers/Fixes

Testing

Tested locally

[codecov]

Codecov Report

Merging #5720 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master    #5720   +/-   ##
=======================================
  Coverage   30.08%   30.08%           
=======================================
  Files         249      249           
  Lines       21455    21455           
  Branches     3113     3113           
=======================================
  Hits         6454     6454           
+ Misses      14725    14722    -3     
- Partials      276      279    +3

Impacted Files	Coverage Δ
app/dashboard/views.py	12.24% <0%> (ø)	⬆️
...rketing/management/commands/no_applicants_email.py	0% <0%> (ø)	⬆️

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