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/regression-test-issue-2190.js

@@ -13,7 +13,7 @@
 // limitations under the License.
 
 try {
-  /(?:(?=x)){1000}xyz/.exec('xyz');
+  /(?:(?=x)){10000}xyz/.exec('xyz');
   assert(false);
 } catch (e) {
   assert(e instanceof RangeError);