Lazy initialize external storages

[PVince81]

Fixed the following external storages to not connect in the constructor,
but do it on-demand when getConnection() is called.

• S3
• SWIFT
• SFTP

Prerequisite for the fix of #10820

Please review/test @butonic @bantu @icewind1991

I tested SFTP (manual+unit tests) and SWIFT (manual+unit tests against devstack) and this change did not break them.

[icewind1991]

Code looks good 👍

[LukasReschke]

Rebase please.

[PVince81]

Rebased

[scrutinizer-notifier]

The inspection completed: 9 new issues, 8 updated code elements

[ghost]

🚀 Test PASSed. 🚀
Refer to this link for build results (access rights to CI server needed):
https://ci.owncloud.org//job/pull-request-analyser-ng-simple/896/
🚀 Test PASSed. 🚀

[LukasReschke]

👍 🎫

[PVince81]

@karlitschek backport to stable7 ? It only affects SFTP, SWIFT and S3 and is a prerequisite for #10820

[karlitschek]

yes. please backport

[PVince81]

I'm on it. There are some conflicts.

[PVince81]

Backported to stable7 as 09d80ac
I also re-ran the unit tests for SWIFT and SFTP.

[butonic]

💣 💣💣 completely breaks s3 💣 💣 💣
$base_url and $param is not remembered as a global variable (and thun used in the connection)

have not had a look at swift or SFTP

please be more thorough when testing files external stuff ...

[LukasReschke]

Filed #11714 to track this properly.

Apologize for missing that on the review, shouldn't have happened and will try hard to prevent such failures in the future. - Seems like I should setup a S3 account...
This is clearly not only @PVince81's fault but also I and @icewind1991 failed here.

Thanks a lot for catching that and sorry again. - I'm just annoyed about this error as you are.

[PVince81]

I didn't test S3. The US buckets are way too slow...
Will fix the issue.

[LukasReschke]

Any chance to have the external storage tests also running on Jenkins? - Wouldn't even have to run on all PRs but at least on the release branches it might be a nice addition.

\cc @DeepDiver1975