Freeze settings v2

[jgur-psyops]

To support arena, we added banks with frozen settings. After some consideration, we have determined that the pool administrator should be able to modify the deposit/borrow limits. Those settings are now configurable even on frozen pools.

Adds a floor to oracle_max_age that is in line with real-world observations of minimum oracle times for txes to actually resolve to avoid a too-low oracle time footgun that renders the pool mostly unusable.

Per discussion, the front end will also enforce the following requirements to be listed on Arena's visible pools:

• Frozen settings - true
• Asset/liability weights - within some mrgn-defined limits
• Deposit/Borrow limits - any, defaults to no cap
• Operational State - active
• Oracle - generated by mrgn (a user-generated or user-supplied oracle might be supported if we whitelist it individually, e.g. a sponsored feed)
• Interest rates - uses mrgn-defined defaults
• Insurance fees - zero (all losses are socialized)
• Group fees - within some mrgn-defined range
• Origination fees - within some mrgn-defined range
• Risk Tier - Collateral
• Asset Tag - Default
• Asset Value Init - no cap
• oracle age - mrgn-defined value (likely 1-2 minutes)
• Permissionless debt settlement - true
• emissions - full configurable, but will not appear on the Arena front end in v1