Add Debian package upload to API

What does this MR do?

This is item 2.6 of #5835 (comment 414103286).

The first user-facing change !

We need to support different file types (see spec/fixtures/packages/debian of !44029 (merged) for an example):

• .deb files: the most common package files
• .udeb files: lightened .deb files, used for debian-installer
• .tar.{gz,bz2,xz,...}: Source files
• .dsc: Source metadata, and list of source files (with hashes)
• .buildinfo: Used for Reproducible builds
• .changes: Upload metadata, and list of uploaded files (all the above)

Uploading with dput will send those files, one at a time (a different HTTP request for each), finishing by the changes file, which triggers the processing.

Screenshots (strongly suggested)

Does this MR meet the acceptance criteria?

Conformity

• I have included a changelog entry, or it's not needed. (Does this MR need a changelog?)
• I have added/updated documentation, or it's not needed. (Is documentation required?)
• I have properly separated EE content from FOSS, or this MR is FOSS only. (Where should EE code go?)
• I have added information for database reviewers in the MR description, or it's not needed. (Does this MR have database related changes?)
• I have self-reviewed this MR per code review guidelines.
• This MR does not harm performance, or I have asked a reviewer to help assess the performance impact. (Merge request performance guidelines)
• I have followed the style guides.

Availability and Testing

• I have added/updated tests following the Testing Guide, or it's not needed. (Consider all test levels. See the Test Planning Process.)
• I have tested this MR in all supported browsers, or it's not needed.
• I have informed the Infrastructure department of a default or new setting change per definition of done, or it's not needed.

Security

Does this MR contain changes to processing or storing of credentials or tokens, authorization and authentication methods or other items described in the security review guidelines? If not, then delete this Security section.

• Label as security and @ mention @gitlab-com/gl-security/appsec
• The MR includes necessary changes to maintain consistency between UI, API, email, or other methods
• Security reports checked/validated by a reviewer from the AppSec team