Improve parsing of SPL2 modules for statement names to handle strings, fields, functions, comments.

[fantavlik]

This PR adds more robust parsing for search statements to exclude cases like local variable assignments within a function:

function foo() {
  $not_a_search = ...
}

or statements that have been commented out:

$use_me = from ...;
/*
$dont_use_me = ...;
*/

[haariskhan902]

This might be a tall ask and is out of scope for this, but are the repeated substring calls suboptimal here? Would it be best to traverse the string via an index like so:

newModule = "";
for (index = 0; index < spl2Module.length; index++) {
    next = spl2Module[indx];
    ...
    // Case logic and all here
    ...
    if (!inBlockComment && !inField && !inString && !inLineComment && braceLevel === 0) {
        newModule += next;

    prev = next;
}

Doing so might fare better for larger modules since we don't need to repeatedly substringify the module.

[fantavlik]

Yes, good suggestion substring made more sense before I rewrote the parsing code but serves no purpose anymore. I made your suggested changes.

[haariskhan902]

Where are we updating prev? I don't see any assignments to prev, specifically nothing like prev = next

[fantavlik]

great catch, it looks like I neglected to add a test that includes string and field escape chars too so let me do that

[haariskhan902]

Approved on my end!