Fix select all features in attribute table

[vaahtokarkki]

Description

Select all action in attribute table selects all features from layer and disrespects any filtering done in the attribute table dialog. With this PR, the select all action will select all features visible in the table.

Fixes #53150
Fixes #55781 as copying features not present in the attribute table yields null values.

[Joonalai]

Nice work!

[elpaso]

Nice work indeed, but it seems to me that there is no consent over the expected behavior here: I have the feeling that all in "Select All" means select all features (including filtered out).

[vaahtokarkki]

Yeah that probably is the case, as it is discussed in #55781 (even though one could argue it to be a bit unexpected behaviour).

Btw @elpaso, could you please review also my other PR #56825 that has been hanging there for over a month already? It should be just a simple bug fix and not a feature request as this turned out to be.

[bloqbreaker]

Nice work indeed, but it seems to me that there is no consent over the expected behavior here: I have the feeling that all in "Select All" means select all features (including filtered out).

While I agree that 'all' means 'all', I believe the question here to be about the context. I stumbled over this topic after having it happening to me as well, because in the context of a filtered attribute table 'all' to me means all that is currently shown in the table >after< filtering. As humans being a creature that a) relies heavily on visual information, even more so when working at a monitor, where we have almost exclusively visual info, and b) relying on context of a situation, I would argue that 'select all' selecting everything, even what might not currently be visible is a fatal UI design flaw. Especially because it appears to happen to many more people than me, else there wouldn't be a discussion. And there is no warning at any point, no info about the extend of what you have selected or otherwise.

I'll continue this at the other (somewhat longer) discussion (#55781) though if I feel like it. Right now I'm just super bummed out and have to try and rescue some data and/or redo everything I have done so far...

[vaahtokarkki]

@bloqbreaker Thanks for the comment, and sorry for any data loss! I highly encourage you to also comment in the longer discussion in the issue you linked, as the comments here might go unnoticed.

One thing I didn't mention in the previous comments: maybe the most problematic issue might be the Ctrl+A shortcut, which is tied to the unexpected behavior of the 'Select All' action in the context of the attribute table. I find it hard to argue why Ctrl+A should select anything else than the contents of the attribute table.