[DASH Flow] Add SaiVal derivative before some arguments of set_flow_entry_attr to make configuration easier

[ShaofengWu123]

This PR adds @SaiVal[type="sai_ip_address_t"] before the following arguments of action set_flow_entry_attr in dash flow:

• underlay0_sip
• underlay0_dip
• underlay1_sip
• underlay1_dip

There are mainly two reasons for doing this:

• Other parts of the dash pipeline do so. For example, in action set_eni_attrs, every argument of type IPv4Address is added a @SaiVal[type="sai_ip_address_t"] before it.
• Generated saithrift rpc can use IP address-related helper functions to assign a value to corresponding arguments instead of directly using a u32 type value, making the code more readable.

[r12f]

ouch! @ShaofengWu123 do you mind to help take this PR to OCP SAI repo asap?

[ShaofengWu123]

ouch! @ShaofengWu123 do you mind to help take this PR to OCP SAI repo asap?

Sure, please check: opencomputeproject/SAI#2101.