User defined default viewer take precedence for rendered factory

[fcollonval]

References

Fix #7776

Code changes

Look first in user overrides list for rendered widget so it takes precedence.

User-facing changes

Some link may open with a different editor if they change the default viewer settings.

Backwards-incompatible changes

N/A

[jupyterlab-probot]

Thanks for making a pull request to jupyterlab!
To try out this branch on binder, follow this link:

[jtpio]

Thanks!

[github-actions]

Benchmark report

The execution time (in milliseconds) are grouped by test file, test type and browser.
For each case, the following values are computed: min <- [1st quartile - median - 3rd quartile] -> max.

The mean relative comparison is computed with 95% confidence.

Results table

Test file	large_code_notebook	large_md_notebook
open
chromium
actual	6320 <- [6937 - 7077 - 7226] -> 7756	3258 <- [3418 - 3491 - 3556] -> 4030
expected	6279 <- [6935 - 7059 - 7157] -> 7751	3298 <- [3429 - 3491 - 3599] -> 3911
Mean relative change	0.3% ± 1.2%	-0.6% ± 1.0%
switch-from
chromium
actual	633 <- [725 - 761 - 888] -> 1296	513 <- [562 - 592 - 703] -> 940
expected	654 <- [715 - 779 - 959] -> 1098	516 <- [574 - 666 - 756] -> 856
Mean relative change	-2.5% ± 4.1%	-4.2% ± 4.1%
switch-to
chromium
actual	800 <- [879 - 914 - 938] -> 1062	661 <- [708 - 736 - 794] -> 859
expected	820 <- [886 - 918 - 950] -> 1075	642 <- [712 - 775 - 812] -> 870
Mean relative change	-1.0% ± 1.4%	-1.7% ± 2.0%
close
chromium
actual	790 <- [888 - 943 - 1184] -> 1386	605 <- [643 - 659 - 677] -> 761
expected	755 <- [897 - 934 - 1190] -> 1335	607 <- [637 - 655 - 676] -> 766
Mean relative change	-0.0% ± 4.5%	0.3% ± 1.3%

Changes are computed with expected as reference.

[krassowski]

This fixes #10875 - should we backport it?

[fcollonval]

This fixes #10875 - should we backport it?

I don't think it fixes that issue because this addresses a corner case: the viewer to pick when a local file is opened from a link in a markdown cell for example). Before this PR, the user settings was ignored when looking for the viewer is that case.

[fcollonval]

@meeseeksdev please backport to 3.6.x