Re-work and rename flex subpackages, and provide shared libraries
This resolves a user request for a shared library (#1327851) and harmonizes
package names and content with Debian and SUSE.
The following subpackage changes have been made:
- Remove and obsolete the flex-devel subpackage containing static libraries
- Provide shared libraries in a new subpackage named libfl2
- Provide development files in a new subpackage named libfl-devel
- Provide static libraries in a new subpackage named libfl-static