- modify Scanner.scanForTextBlock() to add support for \s and
  \"""
- modify Scanner.getLineContent() to add \" support
- fix current position pointer error in Scanner.jumpOverMethodBody()
  and PublicScanner.jumpOverMethodBody()
- add new test to TextBlockTest

Change-Id: Ib587844aecc80c97883ed25e32d7e5667ef15e20
Reviewed-on: https://git.eclipse.org/r/c/jdt/eclipse.jdt.core/+/185711
Tested-by: JDT Bot <jdt-bot@eclipse.org>
Reviewed-by: Jay Arthanareeswaran <jarthana@in.ibm.com>