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 <gballet@gmail.com>

les/utils/expiredvalue.go

@@ -92,7 +92,10 @@ func (e *ExpiredValue) Add(amount int64, logOffset Fixed64) int64 {
 		e.Exp = integer
 	}
 	if base >= 0 || uint64(-base) <= e.Base {
-		e.Base += uint64(base)
+		// This is a temporary fix to circumvent a golang
+		// uint conversion issue on arm64, which needs to
+		// be investigated further. FIXME
+		e.Base = uint64(int64(e.Base) + int64(base))
 		return amount
 	}
 	net := int64(-float64(e.Base) / factor)