accounts/abi: implement new fallback functions (#20764)
- accounts/abi: implement new fackball functions
In Solidity v0.6.0, the original fallback is separated
into two different sub types: fallback and receive.
This PR addes the support for parsing new format abi
and the relevant abigen functionalities.
- accounts/abi: fix unit tests
- accounts/abi: minor fixes
- accounts/abi, mobile: support jave binding
- accounts/abi: address marius's comment
- accounts/abi: Work around the uin64 conversion issue
Co-authored-by: Guillaume Ballet <firstname.lastname@example.org>