Portconfig.ini parser in different applications are expecting different schema

[taoyl-ms]

Currently multiple applications are parsing portconfig.ini independently, and each of them are expecting a different schema. For example, some of them support port speed and/or port index fields while some do not.

We'll need unify the schema for that file and create a single parse to read from that file.

[jleveque]

We also need to enforce a consistent name for the port index column. Some files call it index (e.g., https://github.com/Azure/sonic-buildimage/blob/master/device/dell/x86_64-dell_s6100_c2538-r0/Force10-S6100/port_config.ini), while others call it port (e.g., https://github.com/Azure/sonic-buildimage/blob/master/device/arista/x86_64-arista_7260cx3_64/Arista-7260CX3-C64/port_config.ini).

[jleveque]

Consistent naming convention for column header titles addressed here: #1001. Still need to create a single parser library per language.

[jleveque]

Related to #496

[jleveque]

Resolved with #1072