Uploading folder with wide and deep hierarchy is very slow

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Is your feature request related to a problem? Please describe.
When uploading a folder with a wide and deep hierarchy through the web interface, the process of just creating the folder structure takes very long. All requests are run sequentially and the deeper the hierarchy the more requests each folder needs:

Describe the solution you'd like

1. Run some of the requests in parallel (race conditions on the same folder parent should be avoided, but is probably not needed with no. 2)
2. Reduce the overall number of requests:

• The PROPFINDs for /files and /files/<user> can be removed since we can safely assume that they must exist.
• The second PROPFIND for the target folder should not be necessary, since that one returned 404 the first time (yes this could result in a race condition with another requests, but it can already happen anyway and it's not problematic since we just want the folder to exist).
• With https://github.com/nextcloud/server/pull/53621 all PROPFINDs can be removed as we can just MKCOL the target directory and it will ignore if any of the parents don't already exist. Even the initial PROPFIND that returns 404 can be removed, as it's cheaper to just always MKCOL instead.