Rework RegExp engine and add support for proper unicode matching (#3746)

This change includes several bugfixes, general improvements, and support
for additional features.
- Added full support for web compatibility syntax defined in Annex B
- Implemented parsing and matching patterns in unicode mode
- Fixed capture results when iterating with nested capturing groups
- Significantly reduced regexp bytecode size
- Reduced stack usage during regexp execution
- Improved matching performance

JerryScript-DCO-1.0-Signed-off-by: Dániel Bátyai dbatyai@inf.u-szeged.hu

tests/jerry/string-prototype-trim.js

@@ -85,3 +85,5 @@ assert("\u000A\u000D\u2028\u202911".trim() === "11");
 
 assert("\u0009\u000B\u000C\u0020\u00A01\u0009\u000B\u000C\u0020\u00A0".trim() === "1");
 assert("\u000A\u000D\u2028\u202911\u000A\u000D\u2028\u2029".trim() === "11");
+
+assert ("\u200B".trim() === '\u200B')