Feature request: Make test path as variable

Hi. and thank you so much for this awesome plugin. I have a suggestion.
In [this section](https://github.com/alepez/vim-gtest#switch-files), you said that the default test path is: `test/**/*_test.cpp`. My project currently uses this path: `test/**/**/*_test.cpp`

Is it possible to make it as a variable and user can set it according to his/her needs?
Thank you so much again.