Add Ctrl-M to the tree drop down to open manage trees dialog

[pHiney]

Fixes my annoyance at constantly clicking and scrolling to the bottom of a long list of trees, to find the "Manage Trees" entry and then possibly misclicking and having to do it all again.

Description of the problem being solved:

Technical solution to a management problem

Steps taken to verify a working solution:

• Select the trees tab, select Ctrl-M. See that the "manage trees" dialog opens.
• Select other tabs and select Ctrl-M. Confirm that the "manage trees" dialog DOES NOT open.

Question:

Do we want Ctrl-M or ctrl-m ??

Link to a build that showcases this PR:

N/A

Before screenshot:

After screenshot:

[Regisle]

when adding hotkeys can you also add it to "help.txt" so we can keep better track to them? (and will need to update https://github.com/PathOfBuildingCommunity/PathOfBuilding/wiki/Keyboard-&-Mouse-Shortcuts when merged)

[pHiney]

when adding hotkeys can you also add it to "help.txt" so we can keep better track to them?

didn't know about help.txt