Adding ShowTaskbarSearchBox

[Letouane]

Initial functions permited only to : hide/show Cortana from the taskbar.
Now defining explicitely how to display Cortana.

(error on the last upload : used my personnal preset)
(firts commit ever, be kind please)

[Disassembler0]

Although there is nothing wrong with the tweak itself, there are few points for why I choose not to merge the PR.

The original HideTaskbarSearchBox tweak is aimed to get rid of the control altogether. I see the taskbar element as utterly pointless, because if you want to search for something, since Windows 7 you simply press the ⊞ Win key and start typing. The ShowTaskbarSearchBox counterpart exists only because I aim to offer reverse functions for all the tweaks and it simply reverts the setting to the default value. Originally, on pre-RTM versions, the default was search box, since RTM onwards, the default changed to icon, so yeah, the functions should probably be renamed to reflect the actual behaviour. Moreover, offering multiple choices beyond simple do that - undo that pair is something what I'd like to generally avoid. Although it's possible that in future, some tweak where this would be necessary will come up, in which case I'm gonna revisit your proposal.

Thanks anyway.