Allow editing and other actions on selected Host Aggregate

[hstastna]

Issue: #6227

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Various errors occurred after displaying Host Aggregates from Relationships table of a Cloud Provider and providing selected actions on a selected Host Aggregate. Only tagging and Download worked for selected Host Aggregates. The same problems occurred for actions of Host Aggregates displayed in a list directly thru Compute > Clouds > Host Aggregates and also actions provided from details page of a Host Aggregate. This PR fixes errors and allows us to provide selected actions.

Editing Host Aggregate:
The DoubleRenderError regarding editing a Host Aggregate was fixed by removing an extra unnecessary code here (because we already call javascript_redirect with same parameters here) and adding unless performed? here. But that was not enough, we also had to prevent calling unnecessary show method.

Adding Host to Host Aggregate:
This action did not work because of calling javascript_redirect here and show method here. After solving this problem, I also had to specify the name of the controller for redirecting and setting id properly, too, to make it work.

Removing Host from Host Aggregate:
Similarly as for adding Host to Host Aggregate.

Deleting Host Aggregate:
I've refactored delete_host_aggregates little bit, in host_aggregate controller. I've used checked_or_params here which works well, no matter if params[:pressed] or params[:miq_grid_checks] is set.
I've also had to solve calling show_list and displaying the list of Host Aggregates after deleting the selected ones. This is solved here.
For displaying flash message about deleting Host Aggregates, I had to call flash_to_session here. These changes work well for Host Aggregates displayed also in a nested list or also for individual Host Aggregates (while displaying details page of a Host Aggregate). I've also removed some unnecessary code as add_flash was already called earlier.
But how do we call delete_host_aggregates properly? I had to make another change to solve this (also with solving calling unnecessary show method here). And finally, I've added delete_host_aggregates to routes. The reasons for this change, are, hopefully, obvious.
Also note that, originally, delete_host_aggregates method was in the same file as the button method, which is now in ems_common.rb (see ManageIQ/manageiq#11980).
I've also refactored the specs little bit.

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After:

[hstastna]

@miq-bot add_label bug

[miq-bot]

Checked commits hstastna/manageiq-ui-classic@0af0514~...631f2bf with ruby 2.4.6, rubocop 0.69.0, haml-lint 0.20.0, and yamllint 1.10.0
5 files checked, 0 offenses detected
Everything looks fine. ⭐

[martinpovolny]

This looks good to me codewise.

Can you ask someone to test it in detail in the UI (I do not have much time until the next Monday).

@h-kataria, @ZitaNemeckova, @mzazrivec, any other volunteers?

[ZitaNemeckova]

• Edit from summary - spinner disappears quickly

• Edit from GTL

• Delete from summary

• Delete from GTL

• Add from summary

• Add from GTL - goes to summary after Add / goes to GTL after Cancel

• Removing Host from Host Aggregate from summary

• Removing Host from Host Aggregate from GTL - goes to summary after remove / goes to GTL after Cancel

I dont' have working Provider so all actions end with Error message Unable to update Host Aggregate "overcloud-compute-0": No credentials defined

@hstastna It looks really good 👍 I'm not sure about those two 👆 redirects to "wrong" page. Maybe it should be a followup PR. WDYT?

[hstastna]

@ZitaNemeckova Thanks very moch for testing. That's another issue (what's going on after clicking on Cancel button vs. what's going on after success), and I've seen it also in other screens (other than Hosts or Host Aggregates). I think that it can be fixed via another PR. Maybe I should also open a separate issue for it. What do you think? :)

[ZitaNemeckova]

@hstastna Sounds good to me :)

@martinpovolny Tested in UI. LGTM 👍