Representation of uint64 types

[ckeshava]

I'd like clarification on the representation of UINT64 type in the xrpl.js library. This data type needs to support a maximum value of 18446744073709551615 (in base-10 representation) or 0xffffffffffffffff in base-16 format.

1. The former input causes regular-expression failures in the below unit tests.
2. What are the acceptable forms of BigInt representation? As explained in the comments, 18446744073709551615n causes a typescript compiler error. Whereas BigInt(18446744073709551615) causes a loss of precision. It appears that only BigInt('0xffffffffffffffff') is the format of input.

Reference unit tests: https://github.com/XRPLF/xrpl.js/compare/main...ckeshava:xrpl.js:uint_tests?expand=1