Fix wrong CommandPallete access

[tusharsnx]

Closes: #17032

We were wrongly calling the Ctor of CommandPalette which led to the creation of an uninitialized winrt command palette object, and then OnCreateAutomationPeer() was called on that. This seems to be the cause of #17032.

Validation Steps Performed

• Open WT.
• Try to tear off a tab out of the tab headers view.
• WT doesn't crash.

[DHowett]

thanks!!

[DHowett]

Do you by chance know when this regressed?

[zadjii-msft]

Should we just rename CommandPalette in TerminalPage.xaml to AHHH_DONT_CALL_ME_DIRECTLY_CommandPalette, so that we catch anything else like this?

[tusharsnx]

Do you by chance know when this regressed?

I think it was #15313 which reverted some code that used CommandPalette() prior to #15203. The latter renamed the CommandPalette component to its current name.

The timing was just prefect 😅