[Expansion] - Centralized validation

[gbarkhatov]

It would be good to have a centralized validation method for delegation expansion that checks against the latest parameters, such as:
1. Timelock
2. Amount
3. Max FP
4. …

But of course, u can handle in a seperate PR/issue.
It's none-blocking

Originally posted by @jrwbabylonlab in #1431 (comment)