Pool join/exit validation

[Robiquet]

join:
3.1 The ratio between pool_shares_amount and pool.liquidity_shares_manager.total_shares() must be at least 139_098_411 (1.39...%).
exit:
4.1 If the pool survives the withdrawal (i.e. the user doesn't withdraw the last pool shares), then the new liquidity parameter must be at least 10_000_000_000. Otherwise, the pool isn't liquid enough and the only option to withdraw all of your funds.
4.2 If the pool survives, then the ratio between the remaining pool shares and pool.liquidity_shares_manager.total_shares() (total_shares calculated after withdrawal) must be at least 139_098_411 (1.39...%). Otherwise, the LPs position is too small and the only option is to withdraw all of your funds.