Clean up LISK32 charset handling

[bobanm]

There are a few things in Cryptography element which managed to escape from a code review:

• validateLisk32Address() returns true or never instead of only throwing like most other validate functions
• There are 2 constants in address.ts defining what BASE32 charset is: CHARSET and LISK32_CHARSET
• Constants from address.ts could be moved to constants.ts
• Error messages are not using values from constants but hardcoded literals
• Test assertions do not need return statement