Better error reporting for issues specific to the tool

[shannonwells]

When a transaction is submitted, just the transaction data is displayed, and if it fails, just the enum values are displayed, one for the pallet index in our runtime, and one for the Error enum in the actual pallet. There are some common failures that could be converted to human-readable meanings, rather than having to literally poke through polkadot-sdk code to figure out which pallet and which Error enum emitted the error. Examples:

• balance too low / insufficient funds (all tools)
• signer already approved (multisig signing tool)
• no timepoint (see Date selection for block in time release can result in duplicate code hash & rejection of multisig #8 )

There are probably others, but these 3 are good for now.

To get the index of a pallet in our runtime, see construct_runtime!(...) in runtime/frequency/src/lib.rs

For convenience, the substrate frame pallet code lives here.