Massive Cilium optimization starting in v2.6.0

[mysticaltech]

@M4t7e Contributed to a massive Cilium improvement and optimization in #930.

Basically, Kube-hetzner now makes optimal use of Cilium's full and powerful capabilities.

Changes:

• Fixed decoupling issue between CCM IPAM and the Cilium IPAM. Now Cilium honors the IPAM from the CCM and Hetzner Network Routes are set accordingly to allow native routing directly to pod IPs as well. See also Update handling of custom cluster-cidr #902 (comment)
• Updated Cilium options according to the latest deprecation warnings: https://docs.cilium.io/en/latest/operations/upgrade/#deprecated-options
• The Cilium version is now maintained explicitly. This PR sets it to 1.14.0 and some settings require that as the minimum version.
• Enabled per endpoint routes instead of routing via the cilium_host interface.
• Native routing mode has been added so that even a fully integrated network model (flat model) can be configured with Cilium
• Enabled eBPF-based masquerading, considered the most efficient implementation.
• Added LoadBalancer & NodePort XDP Acceleration (eBPF is operating directly in the networking driver instead of a higher layer)
• Added option to enable the Egress Gateway for Cilium (disabled by default)