share/examples: move examples into appropriate packages

share/examples: move examples into appropriate packages

Allow a new variable SE_xxxPACKAGE to be used to place an example group
into a package.

Move the following examples into existing appropriate packages:

- bhyve examples into FreeBSD-bhyve
- bootforth examples into FreeBSD-bootloader
- csh examples into FreeBSD-csh
- ipfw examples into FreeBSD-ipfw
- jail examples into FreeBSD-jail
- pf examples into FreeBSD-pf
- ppp examples into FreeBSD-ppp
- printing examples into FreeBSD-lp
- uefisign examples into FreeBSD-efi-tools
- ypldap examples into FreeBSD-yp
- hast examples into FreeBSD-hast

Move all other examples into the new 'FreeBSD-examples' package.

This removes a significant number of files from the FreeBSD-utilities
package.

Reviewed by: imp, manu
Pull Request: https://github.com/freebsd/freebsd-src/pull/1176