Update windows installer instructions

Streamline process of installer generation:
1. We don't need to support different installers (with and without JRE), so
   remove unnecessary files.
2. Update and rename script to generate [un]install sections.
3. Update instructions with complete list of components that are required for
MinGW and MSYS components, and exact list of command to execute to generate
installer.
4. Remove script, because time to prepare exact environment it expects would
take same effort as executing those operations manually and because we don't
need two versions of installer there is no duplication of work, that this script
was intending to avoid.

Signed-off-by: Anton Kolesov <Anton.Kolesov@synopsys.com>