Include ODL's BGP to HC minimal distro

Include ODL's BGP to HC minimal distro

Features:
- static bgp instance
- static peer registry (both remote & app peers supported)
- bgp operational state exposed via RESTCONF/NETCONF
- bgp-inet support
- postman collection with examples

TODOs:
- make bgp disabled by default in honeycomb.json (probably bgp should be build using profile
  or allow to filter yangs loaded by SchemaCtx, otherwise footprint will grow)
- update asciidocs for infra module
- SPI for VPP integration:
  - allow RIB changes listeners
  - or writers (that can reject changes) to mirror netconf/restconf design
- expose bgp server & peer cfg via netconf/restconf (currently read from json files)
- test support for all BGP extensions (flowspec BGP needs additional care)
- make bgp extensions fully configurable (probably requires changes in ODL)

Testing

1) start hc distro:
./infra/minimal-distribution/target/minimal-distribution-1.17.07-SNAPSHOT-hc/minimal-distribution-1.17.07-SNAPSHOT/honeycomb

2) run bgp-testtool:
java -jar ./target/bgp-testtool-0.6.3-Boron-SR3-executable.jar
 -ra 127.0.0.1:1790 -la 127.0.0.2:17900 -pr 2 -ll DEBUG --active true -as 65000 -mp true

then GET http://localhost:8183/restconf/operational/bgp-rib:bgp-rib

Change-Id: I156d6a1c79174279db8c8936c40ac1f28e14794c
Signed-off-by: Marek Gradzki <mgradzki@cisco.com>