Add Back button to policy simulation page for non-explorer

[hstastna]

Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=1704395

Back button was missing in policy simulation screen while checking details of selected item. This is related only to non-explorer screens, for example for list of VMs displayed thru provider's details page. For explorer ones, the button was there (see this).

I am also adding another change session[:edit] = @edit. First, @edit with details of policy simulation is set in policy_sim_build_screen method and then forgotten, for non-explorer screens. This caused problems with rendering the selected item's info later, also with clicking on a selected item (quadicon). session[:edit] = @edit needs to be set after policy_sim_build_screen is called.

The fix works also for nested list of Instances.

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After:

[hstastna]

@miq-bot add_label bug, ivanchuk/yes, changelog/yes

[miq-bot]

Checked commit hstastna@663761c with ruby 2.4.6, rubocop 0.69.0, haml-lint 0.20.0, and yamllint 1.10.0
3 files checked, 0 offenses detected
Everything looks fine. 🏆

[skateman]

@hstastna is this a regression? Because I think this thing used to work some time ago and we might have to look into what caused the problem than adding a new button. cc @h-kataria

[hstastna]

I think this is not a regression but I may be wrong. I will try to check this in older versions.

[hstastna]

So I've tested in 5.10 and 5.9 appliance and in both cases, this was the result (after clicking on quadicon):

It looks like this haven't worked at all, in the previous versions. But let's wait for the reporter of the bug and his appliances.

[hstastna]

Update: reporter of the bug cannot test if this is a regression due to https://bugzilla.redhat.com/show_bug.cgi?id=1686619 in 5.9 and also 5.10.

[skateman]