Use startBgpServer() rather than doing things individually, so that we
can follow the logic path of how kube-router actually works better. This
allows us to use annotations rather than set stuff manually and allows
us to test more of the code-path of the NRC.

Additionally, this change allows us to actually test some errors better
such as, make sure that startBgpServer() actually throws the error we
expect when only one part of the prepend ASN annotation is present.
Previously, we were not actually testing this code path.

gobgp 2.27.0
k8s 1.21

Signed-off-by: Mikhail Sakhnov <mikhail@skhnv.me>

* fix(nsc): Overly eager IPVS updating

Switches the endpoint map comparison in OnEndpointsUpdate from being a
DeepEqual, to instead checking that all services exist, and that their
associated endpoints are similar.

Ordering is no longer considered important in regards to the IPVS
update check.

Fixes #1026 

Includes an upgrade to gobgp 2.26.0

* ipset restore: use temporary sets and swap them into the real ones

* move const

* switch to shared tmp ipsets

* preemptively flush tmp set in case it already existed

See the following for more details:
https://github.com/cloudnativelabs/kube-router/security/code-scanning?query=ref%3Arefs%2Fpull%2F1065%2Fmerge+tool%3ACodeQL

See:
https://github.com/cloudnativelabs/kube-router/security/code-scanning/1?query=ref%3Arefs%2Fpull%2F1065%2Fmerge

It is standard practice in Go to not capitalize error messages:
https://github.com/golang/go/wiki/CodeReviewComments#error-strings

See also: https://docs.github.com/en/code-security/secure-coding/configuring-code-scanning

Configuration taken from: https://github.com/github/codeql-action/blob/main/README.md#usage

Add an extra annotation for service in order to generate haipin related
iptables rules for externalsIps of the service.

glog is effectively unmaintained and the kubernetes ecosystem is mainly
using its fork klog

Fixes: #1051

* Remove vendor directory

* Fix symlink

* Update golang version to 1.15.10

* Update dependencies

* doc(ecmp_vip.go): add info around extra withdraw

Rename getWithdraw to make it more explicit what its doing here. Also
add documentation as to why this is needed on Update and not
Create/Delete as well as why we only treat externalIPs.

* fix(ecmp_vip.go): remove superfluous AddPolicies

AddPolicies is already called downstream of nrc.OnEndpointsUpdate() so
there is no need to do it here as well, the only result is that this
expensive operation and idempotent operation is run twice.

* feat: better handling of headless services

Also introduces a consolidated Service utilities section for controller
functionality related to services that is shared.

* fix: add logging back to tryHandleServiceDelete

fixes #1035