Fix home/end, url handler, typing nav, and dependency double click

[HebaruSan]

Problem

If you do any of the following:

• Press Home on the mod list
• Press End on the mod list
• Invoke the URL handler
• Start typing a mod name on the mod list
• Double click a mod in the mod info dependency tree

... this exception occurs:

System.InvalidOperationException: Die aktuelle Zelle kann nicht auf eine unsichtbare Zelle festgelegt werden. (Rough translation: the current cell can't be set to an invisible cell)
   bei System.Windows.Forms.DataGridView.set_CurrentCell(DataGridViewCell value)
   bei CKAN.Main.ModList_KeyDown(Object sender, KeyEventArgs e)
   bei System.Windows.Forms.Control.OnKeyDown(KeyEventArgs e)
   bei System.Windows.Forms.DataGridView.OnKeyDown(KeyEventArgs e)
   bei System.Windows.Forms.Control.ProcessKeyEventArgs(Message& m)
   bei System.Windows.Forms.DataGridView.ProcessKeyEventArgs(Message& m)
   bei System.Windows.Forms.Control.WmKeyChar(Message& m)
   bei System.Windows.Forms.Control.WndProc(Message& m)
   bei System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)

Cause

These all work by setting ModList.CurrentCell to a row's third cell, for reasons explained here:

CKAN/GUI/Main.cs

Lines 1055 to 1056 in 3bc5376

	// Setting this to the 'Name' cell prevents the checkbox from being toggled
	// by pressing 'Space' while the row is not indicated as active.

However, as of #2671, the third cell is Replace instead of Name, and as of #2690, it's hidden most of the time. A hidden cell cannot be the current cell, so an exception is thrown. This is essentially the same problem as #2703, but it's not specific to the mark-all-updates operation.

Changes

Now we look for usable columns in this order:

1. The current column, if any, to avoid scrolling horizontally
2. The first visible non-checkbox column, if any
3. The Installed checkbox column (always visible fallback)

In addition, the fix for #2704 is modified to use this same logic. I think the original reasoning from the comment quoted above applies here, and so we should avoid setting focus to checkboxes when we can.

Fixes KSP-CKAN/NetKAN#7108.

[DasSkelett]

Why does it show my name for the label remove (and in other occasions)?
Is this because I am the last one who logged in on the Waffel page?

[HebaruSan]

Yeah, that Waffle thing likes to make automatic changes for reasons I don't understand. It did it in my name for a while when I first joined as well.

[DasSkelett]

Works fine, no errors, no unwanted horizontal scrolling or something.

[HebaruSan]

Welcome to the team by the way, @DasSkelett! I'm excited about having a more... active... collaborator. :)

[DasSkelett]

Thanks. You tell me something, that was quite a hot start with you going on vacation, and @politas releasing a new major version, and all that exactly in those two weeks where I had training every two days for a fire brigade performance test....