Admin Enable MPLS on RIFs if it is supported

[itskittycisco]

Pre-submission checklist

• I've ran the linters locally and fixed lint errors related to the files I modified in this PR. You can install the linters by running pip install -r requirements-dev.txt && pre-commit install
• pre-commit run

Summary

MPLS can be enabled on router interface using the SAI attribute SAI_ROUTER_INTERFACE_ATTR_ADMIN_MPLS_STATE. As per the SAI spec, the default for SAI_ROUTER_INTERFACE_ATTR_ADMIN_MPLS_STATE is false and needs to be enabled by the NOS. This is a fix to enable SAI_ROUTER_INTERFACE_ATTR_ADMIN_MPLS_STATE on L3 AC ports and SVIs.

Test Plan

Executed all the MPLS FBOSS test cases and verified they are passing.
HwMPLSTest/0.ExpiringTTL
HwMPLSTest/0.Php
HwMPLSTest/0.Pop
HwMPLSTest/0.Swap
HwMPLSTest/1.ExpiringTTL
HwMPLSTest/1.Php
HwMPLSTest/1.Pop
HwMPLSTest/1.Swap
AgentTrunkLoadBalancerTest.ECMPFullTrunkHalf4X2WideTrunksV4MplsPhpFrontPanelTraffic
AgentTrunkLoadBalancerTest.ECMPFullTrunkHalf4X2WideTrunksV4MplsSwapFrontPanelTraffic
AgentTrunkLoadBalancerTest.ECMPFullTrunkHalf4X2WideTrunksV6MplsPhpFrontPanelTraffic
AgentTrunkLoadBalancerTest.ECMPFullTrunkHalf4X2WideTrunksV6MplsSwapFrontPanelTraffic
AgentTrunkLoadBalancerTest.ECMPFullTrunkHalf4X3WideTrunksV4MplsSwapFrontPanelTraffic
AgentTrunkLoadBalancerTest.ECMPFullTrunkHalf4X3WideTrunksV6MplsPhpFrontPanelTraffic
AgentTrunkLoadBalancerTest.ECMPFullTrunkHalf4X3WideTrunksV6MplsSwapFrontPanelTraffic
HwTrunkLoadBalancerTest.ECMPHalfTrunkFull4X2WideTrunksV4MplsPhpFrontPanelTraffic
HwTrunkLoadBalancerTest.ECMPHalfTrunkFull4X2WideTrunksV4MplsSwapFrontPanelTraffic
HwTrunkLoadBalancerTest.ECMPHalfTrunkFull4X2WideTrunksV6MplsSwapFrontPanelTraffic
HwTrunkLoadBalancerTest.ECMPHalfTrunkFull4X3WideTrunksV4MplsPhpFrontPanelTraffic
HwTrunkLoadBalancerTest.ECMPHalfTrunkFull4X3WideTrunksV4MplsSwapFrontPanelTraffic
HwTrunkLoadBalancerTest.ECMPHalfTrunkFull4X3WideTrunksV6MplsPhpFrontPanelTraffic