Make debug UI search bar more compact, avoid overflow

[leonardehrenfried]

Summary

This PR tidies up the search bar of the debug UI:

• it makes the input boxes take up less room
• it combines the Route and GraphiQL into a single button group with an icon instead of the word "GraphiQL"
• it makes the paging buttons a little smaller and less conspicuous

This also avoids some ugly overflow issues on even medium sized screens.

Before

After

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 69.83%. Comparing base (f285066) to head (0be4f9f).
Report is 15 commits behind head on dev-2.x.

Additional details and impacted files

@@            Coverage Diff             @@
##             dev-2.x    #6091   +/-   ##
==========================================
  Coverage      69.83%   69.83%           
- Complexity     17456    17457    +1     
==========================================
  Files           1974     1974           
  Lines          74600    74600           
  Branches        7636     7636           
==========================================
+ Hits           52098    52099    +1     
+ Misses         19854    19853    -1     
  Partials        2648     2648           

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