[PAN-2959] return the ethereum address of the privacy precompile from priv_getPrivacyPrecompileAddress

[iikirilov]

PR description

Returns the ethereum address of the privacy precompile contract rather than the raw integer value of the position of the precompile.

See the discussion in #1650

Fixed Issue(s)

PAN-2959

[MadelineMurray]

I tested this and got the following result:
{
"jsonrpc": "2.0",
"id": 1,
"result": {
"empty": false,
"zero": false,
"arrayUnsafe": "AAAAAAAAAAAAAAAAAAAAAAAAAH4="
}
}

[iikirilov]

Sorted and tested with postman

{
    "jsonrpc": "2.0",
    "id": 1,
    "result": "0x000000000000000000000000000000000000007e"
}