solana-watchtower: add minimum delegated option

[olivbau]

Problem

It would be useful to have a --minimum-delegated <SOL> option to receive a warning if the delegated SOL amount falls below a specified threshold.
This would allow to know: if we fall below a profitability threshold, or ensure we have the minimum 100 SOL required by the SFDP, or be alerted if we lose the foundation's delegation.

Proposed Solution

Adding a --minimum-delegated <SOL> option

[github-actions]

This repository is no longer in use. Please re-open this issue in the agave repo: https://github.com/anza-xyz/agave