Failing test with Solidity 0.8

[oneeman]

Expected Behavior

Tests should pass when you have current version of Solidity installed

Current Behavior

If you have version 0.8 of solc installed (not the javascript solidity compiled but the C++ version), you get this failure:

--- FAIL: TestSolidityCompiler (0.07s)
   solidity_test.go:47: error compiling source. result map[]: json: cannot unmarshal array into Go struct field .Contracts.Abi of type string
FAIL
FAIL	github.com/ethereum/go-ethereum/common/compiler	0.180s
FAIL

With older versions it passes, and if you don't have it installed the test is skipped so it also passes.

The fix for this is to cherry-pick ethereum/go-ethereum#22092. Once we do that we may also want to have solc installed in our CI setup so that this test can actually run there too.