Provide an easy to enlarge/shrink the size of an array data variable in linear view

[xusheng6]

This is the residual of https://github.com/Vector35/binaryninja-api/issues/1937. I previously suggested that we should provide a way to enlarge/shrink the size of an array using the +/- key, but - is already used for switching the sign of an integer variable. So we will need to pick a different key. Nevertheless, I think the functionality is worthy to have.

[psifertex]

+ and SHIFT + (or =) maybe?

[psifertex]

Related: when we have "hotkey layers" selectable at startup in the welcome wizard the "ida compatibility mode" should be able to set these as an IDA user would expect.