feat(server): allow to override filename when using random_url

[tessus]

Description

curl -F "file=@x.txt" -H "filename:override.txt" http://localhost:8000

Even if random_url is set, the filename will be override.txt (the name specified in the header filename).

Motivation and Context

See issue #217

closes #217

How Has This Been Tested?

• manually
• cargo test
• fixtures

Changelog Entry

### Added

- Allow to override the filename when using `random_url`

Types of Changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation (no code change)
• Refactor (refactoring production code)
• Other

Checklist:

• My code follows the code style of this project.
• I have updated the documentation accordingly.
• I have formatted the code with rustfmt.
• I checked the lints with clippy.
• I have added tests to cover my changes.
• All new and existing tests passed.

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (2003abe) 70.11% compared to head (c7b8a11) 70.88%.
Report is 1 commits behind head on master.

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Additional details and impacted files

@@            Coverage Diff             @@
##           master     #233      +/-   ##
==========================================
+ Coverage   70.11%   70.88%   +0.76%     
==========================================
  Files          11       11              
  Lines         609      625      +16     
==========================================
+ Hits          427      443      +16     
  Misses        182      182              

Flag	Coverage Δ
unit-tests	70.88% <100.00%> (+0.76%)	⬆️

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[tessus]

I saw your blog post and checked out your talk about ratatui. It was great and it looked like you had a lot of fun. (I seriously enjoyed you skipping the emacs slide.) Argh, too bad I didn't get a sticker. ;-)

Btw, is there still anything open for my PRs that I haven't addressed?

[orhun]

Hey @tessus! Thanks for watching my talk and your comments. I highly appreciate it.

I was not able to take a look at PRs but now I have some free time. Will add a review soon! Sorry for the wait.

[orhun]

Just minor points 🐻

[orhun]

Awesome!