denominated units for balances in events (use-ink#750)

* denominated units for balances in events

* fmt and changelog

* denominated input for balances

* fix spelling

* add test for incorrect token symbol

* optimise rpc calls for token metadata

* bump subxt, add Compact compatibility

* replace f64 with rust_decimal

* more comprehensive denomination

* covering edge case with small values

* more tests and docs

* context for balance overflows

* tested conversion from u128

* more tests and better conditionals

* include suggestions from review

* apply changes from review

* inline unwrap and formatting

* more clarity in string parsing for balances

* checked mul and renamed Kilo symbol

* better comments for error and bumped wasm-opt

Author: German

CHANGELOG.md

@@ -31,6 +31,7 @@ release of `ink!`. It is *not* backwards compatible with older versions of `ink!
 
 ### Added
 - `--output-json` support for `call`, `instantiate` and `upload` commands - [#722](https://github.com/paritytech/cargo-contract/pull/722)
+- Denominated units for Balances - [#750](https://github.com/paritytech/cargo-contract/pull/750)
 - Use new ink entrance crate - [#728](https://github.com/paritytech/cargo-contract/pull/728)
 
 ### Fixed