### Describe the issue

I added a second new wallet2.dat. Now I wanted to encrypt it, but `bitcoin-cli help` does not show the command to do so, I need to use `bitcoin-cli -rpcwallet=wallet2.dat help`. This is very un-intuitive, and bad for a help function.

### Can you reliably reproduce the issue?

1. have an encrypted default wallet
2. add new multi wallet wallet2.dat via config file or cmd line options
3. naive `bitcoin-cli help` does not show command to encrypt second wallet.

### Expected behaviour

All wallet encryption, lock and unlock commands should be shown unconditionally in `bitcoin-cli help`.

The dynamic hiding of some lines is arguably worse than the benefit with multiple wallets.

### Actual behaviour

`bitcoin-cli help` shows only wallet encryption commands appropriate for the default wallet.

### What version of bitcoin-core are you using?

bitcoind 0.15.0.1~dfsg-1
deb http://ppa.launchpad.net/luke-jr/bitcoin-core-bip148-unofficial-builds/ubuntu zesty main

### Machine specs:
- OS: Debian 9.2

"\nExamples:\n"
            + HelpExampleCli("getnewaddress", "")
            + HelpExampleRpc("getnewaddress", "")
        );
    LOCK2(cs_main, pwallet->cs_wallet);
    
    std::string strAccount;
    if (!request.params[0].isNull())
        strAccount = AccountFromValue(request.params[0]);
    if (!pwallet->IsLocked()) {
        pwallet->TopUpKeyPool();
    }
    
    CPubKey newKey;
    if (!pwallet->GetKeyFromPool(newKey)) {
        throw JSONRPCError(RPC_WALLET_KEYPOOL_RAN_OUT, "Error: Keypool ran out, please call keypoolrefill first");
    }
    CKeyID keyID = newKey.GetID();
    pwallet->SetAddressBook(keyID, strAccount, "receive");
    return EncodeDestination(keyID);
}
CTxDestination GetAccountAddress(CWallet* const pwallet, std::string strAccount, bool bForceNew=false)
{
    CPubKey pubKey;
    if (!pwallet->GetAccountPubkey(pubKey, strAccount, bForceNew)) {
        throw JSONRPCError(RPC_WALLET_KEYPOOL_RAN_OUT, "Error: Keypool ran out, please call keypoolrefill first");
    }
    return pubKey.GetID();
}
UniValue getaccountaddress(const JSONRPCRequest& request)