Added support for "UNDERLAY_SET_DSCP" and "UNDERLAY_SET_DSCPV6" tables (

#3307)

What I did
This PR adds the logical table UNDERLAY_SET_DSCP and UNDERLAY_SET_DSCPV6.
This feature allows SONIC to match an ingress L4 packet and change the DSCP field of the outer header when the packet is egressing. These tables are only created on Cisco-8000, Mlnx and VS platforms.
The PR also adds support to check if the platform supports the following SAI attributes.
SAI_SWITCH_ATTR_ACL_USER_META_DATA_RANGE
SAI_ACL_ENTRY_ATTR_ACTION_SET_ACL_META_DATA
SAI_ACL_ENTRY_ATTR_FIELD_ACL_USER_META