feat: Add config to customize outDir

[aklinker1]

This closes #257.

// wxt.config.ts
import { defineConfig } from 'wxt';

export default defineConfig({
  outDir: "dist",
});

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[codecov]

Codecov Report

Attention: 5 lines in your changes are missing coverage. Please review.

Comparison is base (7cef768) 64.28% compared to head (410045f) 64.31%.

Files	Patch %	Lines
src/core/utils/building/get-internal-config.ts	28.57%	5 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #258      +/-   ##
==========================================
+ Coverage   64.28%   64.31%   +0.02%     
==========================================
  Files          76       76              
  Lines        6029     6039      +10     
  Branches      489      490       +1     
==========================================
+ Hits         3876     3884       +8     
- Misses       2116     2118       +2     
  Partials       37       37              

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