[Grbl_Esp32 PR#717] Settings filtering via regular expressions

Implements only the most basic – and the most
useful – special characters – ^$.*

If the search string does not contain a special
character, it is interpreted as before. Otherwise
the match is either more strict if anchored by
^ or $, or less strict if it contains a * wildcard .

Some examples:

$y – settings that contain y (as before)
$^y – settings that start with y
$y$ – settings that end with y
$^y*pin – settings that start with y and contain pin
$^y*rd$ – settings that start with y and end with rd

Note that $x is a classic grbl command as always. If you want to see settings that contain x, you can write $x. For settings that start with x, use $^x . In general, this works with any existing Grbl command – by inserting a , you can force it to be interpreted as a setting instead of a command.