Add bulk upload

[artonge]

Fix: #28443

The PR adds a new DAV plugin to handle requests on the /dav/bulk endpoint.

• The endpoint path is open to discussion.
• A new capability that the clients can check: bulkupload

Request templates

--boundary_bec011bf527a43d6
X-File-Path: /bulk_upload/boundary_bec011bf527a43d6_2_10/bb0fff48c6c9b4e9.txt
X-File-Mtime: 1632920977
X-File-Md5: f454251fe1ad474229e7e364a31c1e18
Content-Length: 10

This is a file content that ends with a new line.

--boundary_bec011bf527a43d6
X-File-Path: /bulk_upload/boundary_bec011bf527a43d6_2_10/2d5d1ae90a99cdf7.txt
X-File-Mtime: 1632920977
X-File-Md5: 40b0d4f753a86c333625344342a35d2a
Content-Length: 10

This is a file content that does not end with a new line.
--boundary_bec011bf527a43d6--

• Where bec011bf527a43d6 is a random string
• Headers and file content are separated by one and only one blank line
• File content will be read according to their Content-Length header

Response template

{
    "/path/for/file/n/1": "ETag of the written file",
    "/path/for/file/n/2": "ETag of the written file",
    ....
}

Benchmarks

This PR contains some benchmarks written in bash. They are be flexible enough to test different file counts, file sizes, bandwidth and concurrency.

[artonge]

Should use a different URL. With this you will break the dav endpoint for a user with userid bulk.

Changed to dav/bulk inspired by chunked upload that sits at dav/upload/...

[skjnldsv]

Code looks good. Thanks for the tests too! 👍

[juliusknorr]

Tested with some small adjustment that would need a fix, works good with that otherwise and code also looks nice an clean 👍

[PVince81]

Code looks good in general, great to see many tests.
I only had minor comments

👍

[skjnldsv]

Tests failure unrelated

[skjnldsv]

Once @juliushaertl confirmed, we can get this in 🚀

[juliusknorr]

Pushed a fix for the failing capabilities test