[feature] Bot should allow non-EIP changes

[lightclient]

After 1 editor approval, the bot should allow non-EIP changes like to the pages infra. See this PR as an example: ethereum/EIPs#3581

[alita-moore]

This is accomplished by b9e9330

(details included in commit comments)
This implements a few features:

• eip authors can also make changes to the assets file which will allow any changes so long as the eip passes; i.e. I can do whatever I want to assets/eip-2/.. if I (at the same time) make changes to EIPs/eip-2.md and that is eligible for auto-merge.
• if an editor approves then any non eip file will pass

I also made a few cleanups

• better error handling
• cleaner code
• more tests
• conitnuing transition to class based approach (I'm converting old style to new style whenever I make changes to that file