feat request: report to show which got migrated

[Yiyiyimu]

Proposal

Aim

Since we're at the early stage, and there would always be some configuration could not be migrated from kong, it would be a good idea to generate a report after the migration, to inform users what has been migrated automatically and what should be done manually

Output Format

1. Output would be show the kong.yaml and each line would be painted as green or red, where green means "migrated" and vice versa. There are two possible way to achieve it, as I could think of right now, is to generate an HTML file or output the colored result in shell. The first one could persist and the second one could work in non-GUI supported environment. Need some suggestions on the choices.
2. Show a list that what we could migrate what not, which keeps the same pattern and which not, just like #16
3. Show what APISIX supports but Kong not supports, to inform what else could users do

Timeline:

not decided yet