RIS: Implement initial dump signaling in ObserveFIB

Add LPM call to riscli

Fix BMP error logging (add address)

Check if router was removed before trying to reconnect

Add description field to PeerConfig and BGP API

When creating a BGP peer the description field can be filled as well.
This can then be exported via API.

Add functions to AdjRIBIn/AdjRIBOut for RIS

The funtions RegisterWithOptions(), LPPM(), Get() and GetLonger() need
to be exposed by AdjRIBIn/AdjRIBOut. This makes these RIBs usable in
much the same way as LocRIB for the RIS.

Fix crash on route withdrawal with addpath

If addpath is enabled rx then adjRIBIn.RemovePath() will access a member
of p. As p might be nil (e.g. called by fsm_address_family withdraw())
we need to check for this before accessing it.

Allow multiple AFISAFIs in AddPath capability

RFC7911 sec 4 allows multiple AFISAFIs in a single AddPath capability
entry, which also must be presented in a single capability message.
Without this patch the AddPath capability of a peer advertising multiple
AFISAFIs cannot be parsed and the connection will fail.

RFC2545 section 3 paragraph 2 allows for a next-hop field length of 32.
In this case two IPv6 addresses are being sent, first the global
address, then the link local address. For now we are just ignoring the
link local address and parsing only the first.

Without this patch Bio will not be able to talk to BGP spekaders using
this features. An UPDATE mesage containing such a next-hop field would
result in the following error:

Failed to decode BGP message: Failed to decode message: Unable to decode path attr: Failed to multi protocol reachable NLRI: Unable to decode MP_REACH_NLRI: Failed to decode next hop IP: byte slice has an invalid length. Expected either 4 (IPv4) or 16 (IPv6) bytes but got: 32

Co-authored-by: Daniel Czerwonk <czerwonk@users.noreply.github.com>

* Accept all RFC4486 bgp error subcodes

Bio-BGP used to only decode AdministrativeShut and AdministrativeReset
error subcodes when error code "Cease" was sent by a BGP peer. Other BGP
packets could not be decoded. With this commit Bio-BGP accepts and
decodes all error codes defined in RFC4486.

* Set OtherConfigChange to value defined in RFC4486

In the risserver every bmp server is identified by its address,
specified in the config, but the GetRouters() grpc only presents us with
the name acquired via the BMP session. To clarify the field usage the
router field is renamed to sys_name and an address field is added. The
address field is of type string to match the other grpc methods, which
require a router address to be specified as string.

Co-authored-by: takt <oliver.herms@exaring.de>

Fix BMP label names/combinations

* riscli dump-loc-rip: Dump IPv4/IPv6 routes

By default riscli dump-loc-rib will now dump IPv4 and IPv6 routes. The
flags -4 and -6 have been added to restrict dumping to a single address
family.

* riscli dump-loc-rip: Handle EOF from API

* Remove unused function

This unused function triggered go vet

github.com/bio-routing/bio-rd/syscallwrappers
[error]syscallwrappers/syscalls_linux.go:75:9: possible misuse of unsafe.Pointer

* Remove unreachable code

* Use keyed syntax for composite literals

* Remove copies of mutex locks

Refactor net API to use pointers when working with protos