Allow users to specify project directory with text input

[gregorbj]

The Logic Laboratory interface has a point and click interface for users to identify their project directory. The interface uses the shinyFiles which implements a file chooser interface which is OS agnostic although it is much less responsive on Windows than on Linux (Ubuntu). The point and click approach can be tedious. If the user knows the path name, it would be nice to allow them to specify it in the function call to runLogicLab and also have a text box input that could be used to specify it in the interface as an alternative to using the point and click method.

[gregorbj]

In addition to specifying the project directory in the runLogicLab function call, include a text box in the directory choosing interface. The text box will identify the chosen directory. It can also be used to input a project directory. Include code to check whether the directory is valid.