Write a function named rgbToHexColor that takes an rgb color code string in the format of "rgb(r, g, b)"
and returns the equivalent hexadecimal code string in the format of "#RRGGBB" where "r", "g", "b" are the integer values corresponding
to the hexidecimal values "RR", "GG", "BB" respectively. Recall that the range of a two-digit hexidecimal code is
"00" to "FF" which corresponds to the integer range 0 to 255, inclusive ("F" has a decimal value of 16).
For example, the call rgbToHexColor("rgb(0, 0, 0)") should return the string "#000000" and the call rgbToHexColor("rgb(192, 255, 238)") should return the string "#C0FFEE".
You may assume the passed string is in the specified rgb string format (maintaining casing and spacing) and each
rgb value in the string is an integer value between 0 and 255 (inclusive).
