format_p_val: Format p-value with a specified significant digit cutoff
In graggsd/sgcleanup: Useful Functions to Clean and Reshape Data

Takes a set of p-values, rounds to the specified significant digits, and convert values that are less than the specified cutoff to "<'cutoff'". Maintains consistent numbers of significant digits.

1 2	format_p_val(x, digits = 3, cutoff_action = "inequality", format_sci = NULL)

`x`	A vector of p-values
`digits`	how many significant digits are to be used.
`cutoff_action`	Determines the behavior of the function for values that are less than the specified number of digits. If set to `"inequality"`, then the function replaces these values with `"<cutoff"`. If set to `"sci"`, then the values are converted to scientific notation.
`format_sci`	A string with which to replace the standard "e" scientific notation.