Add "divide" and "multiple" to Uint64

[fboucquez]

Atm, the way we convert from an absolute value to a relative value is using:

const relative = absoluteUint64.compact() / Math.pow(10, config.tokenDivisibility);

The absoluteUint64.compact() may fail if the absoluteUint64 is >= 2^53.

The compact is used because our native UInt64 doesn't have natives division or multiplication like we do have addition and subtraction.

Question, the TS SDK has a dependency to the "long" package.

https://github.com/nemtech/symbol-sdk-typescript-javascript/blob/main/package.json#L109

https://www.npmjs.com/package/long

Should we use the library instead of having our own custom Uint64? Why using both RawUInt64 and Long?