Allow TNetXNGFile to use the http protocol

[ffurano]

TNetXNGFile was not working correctly when given http URLs. This PR fixes that and unlocks progress on those http/s3 matters

[jblomer]

Thank you for the patch!

If I understand correctly, this will make XRootD the handler for HTTP(S) instead of DAVIX. This is a significant change which, I think, requires more testing. E.g., what happens if a version of XRootD is linked that does not support HTTP. Also, it may need a fallback (for some time) in the same way that Davix had a fall back to the old TWebFile.

What about the dav(s) and s3(s) protocol identifiers: should they be deprecated (the PR suggests that).

[github-actions]

Test Results

    22 files      22 suites   3d 7h 5m 31s ⏱️
 3 850 tests  3 847 ✅  1 💤 2 ❌
76 007 runs  75 985 ✅ 18 💤 4 ❌

For more details on these failures, see this check.

Results for commit d0bd605.

♻️ This comment has been updated with latest results.

[ffurano]

Hi Jakob,

what you mention will be among the next steps, and it will take longer. I did not intend to change the default config of the root plugin manager, so XrdCl shall not substitute Davix by default.

The 1-line code change removes the wrong bit in root that was preventing XrdCl from being invoked with non-xroot protocols. For some reason the change in the plugin manager slipped into. My mistake. I'll redo it.

Thank you for the patch!

If I understand correctly, this will make XRootD the handler for HTTP(S) instead of DAVIX. This is a significant change which, I think, requires more testing. E.g., what happens if a version of XRootD is linked that does not support HTTP. Also, it may need a fallback (for some time) in the same way that Davix had a fall back to the old TWebFile.

What about the dav(s) and s3(s) protocol identifiers: should they be deprecated (the PR suggests that).

[amadio]

Looks good now. I will try this with https://github.com/root-project/analysis-grand-challenge over HTTP and post some results here later.