chore(collections): sort exports in `mod.ts`

[mbhrznr]

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during the implementation of https://github.com/denoland/deno_std/pull/4710 i noticed that the exports were unsorted. this pr aligns mod.ts' exports statements with the order of the exports property in the corresponding deno.json file.

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 91.48%. Comparing base (6deab72) to head (d5c5bcf).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #4712   +/-   ##
=======================================
  Coverage   91.48%   91.48%           
=======================================
  Files         477      477           
  Lines       37268    37268           
  Branches     5316     5316           
=======================================
  Hits        34093    34093           
  Misses       3119     3119           
  Partials       56       56           

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