Dont panic!: General rework to remove all panic!, assert! & .unwrap() from library

[guilledk]

NOTES:

• Ideally this would be v0.4.0 of the library increased from v0.3.1 to indicate API breaking changes
• To check for panics / code smells:

cargo test && cargo clippy --all -- \
    -D clippy::unwrap_used \
    -D clippy::expect_used  \
    -D clippy::panic \
    -D clippy::unimplemented`

API Changes:

• Make Packer trait's unpack() return a Result<usize, PackerError> intead of just usize
• Remove panics from chain stuct constructors, implement From/TryFrom/FromStr traits instead
• Implement Display trait which automatically grants to_string for chain structs

Additions:

• Implement FromStr many integer types for Name
• Implement From<u64> for Name
• Add .to_string() to TimePoint & TimePointSec
• Add BlockTimestamp which is the slot based time point sec
• Add serde name serializers in order to be able to do ABI json dumps
• Add ABI type resolver system
• Add ShipABI which represents the ABI that state_history_plugin sends as first message representing the session types
• Add PartialEq to authority structs
• Make some chain structs fields public like in ExtendedAsset, PackedTransaction & Signature
• Make BinaryExtension's inner value public
• Derive Debug on Checksum512
• Implement FromStr for PrivateKey