Fix propfind type of subnodes with depth >= 1

[n-peugnet]

With properties manually added in a plugin using the propFind event like in this example: #482 and with depth >= 1, the subnodes' propfind's type was incorrectly deduced.
This resulted in custom properties only being added to the first node and not on the subnodes.

[codecov]

Codecov Report

Merging #1344 (09bf553) into master (d762b19) will not change coverage.
The diff coverage is 100.00%.

@@            Coverage Diff            @@
##             master    #1344   +/-   ##
=========================================
  Coverage     97.31%   97.31%           
  Complexity     2806     2806           
=========================================
  Files           174      174           
  Lines          7975     7975           
=========================================
  Hits           7761     7761           
  Misses          214      214           

Impacted Files	Coverage Δ
lib/DAV/Server.php	96.58% <100.00%> (ø)

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[n-peugnet]

I added a test case and we can see that it fails on master:

There was 1 failure:

1) Sabre\DAV\ServerPropsTest::testPropFindEmptyBodyDepth1Custom
Response should contain 5 elements
Failed asserting that 1 matches expected 5.

/home/nicolas/Source/php/dav/tests/Sabre/DAV/ServerPropsTest.php:93

[kesselb]

Hey @n-peugnet 👋

please rebase your branch to have a recent CI run.

[n-peugnet]

Done @kesselb

[n-peugnet]

@phil-davis, could you maybe approve this PR to run the GitHub workflow ?

I have run the tests locally and everything is working fine.

[phil-davis]

While I was looking, I refactored some identical preg_replace "magic" in the test code so that it is in a separate function.