Ensure consistency amont camel case vs snake case

[xibz]

The links spec introduced snake casing, instead of camel casing. So we should ensure that these get moved over to camel casing.

These 3 are what I found:

1. link_type
2. context_id
3. chain_id

We should also add a linter to ensure snake casing isn't added in any future proposals.

[davidB]

@xibz, If ok, you can close this issue?