Allow colon in route after path param

[evanrolfe]

The current router implementation does not allow for colons in the route if they are immediately following a path parameter, this prevents us from following the Google API specification.

For example, I was unable to define a route which would match a URL like this: POST /files/1234:delete where 1234 should map to a :fileId path param. This PR fixes that.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 94.04%. Comparing base (f24aaff) to head (8b6130a).
⚠️ Report is 20 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2847      +/-   ##
==========================================
+ Coverage   93.25%   94.04%   +0.79%     
==========================================
  Files          39       39              
  Lines        4652     3826     -826     
==========================================
- Hits         4338     3598     -740     
+ Misses        218      134      -84     
+ Partials       96       94       -2     

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