Add sort-keys rule

[naltatis]

I'd like to have a rule that ensures that tables and keys are in alphabetical order. Similar to e.g jsonc/sort-keys.

# ✓ GOOD
[alpha]
y = 2
z = 3

[beta]
x = 1

# ✗ BAD
[beta]
x = 1

[alpha]
z = 3
y = 2

[andig]

I guess comments are a problem when sorting?

[ota-meshi]

Thank you for the rule suggestions. That rule sounds good to me.