Simplify logic for skipping braces/brackets/parentheses.

No matter what the elements are, any comma within a
brace/bracket/parenthesis pair does not belong to the array we are
looking at.
Split out control structures whitespace sniffs.

These make better sense as separate sniffs, and there are definitely
cases where it would error that we don't want as errors.  For example:
<?php
if (
    $foo ||
    $bar
) {
    echo "Stuff";
}

where it wanted us to change that to:
<?php
if ($foo ||
    $bar) {
    echo "Stuff";
}
FIXME: make all multiline bracket pairs require further indentation.