fix all bits broken by viper API changes (#5982)

github.com/spf13/viper's recent releases introduced a semantic
change in some public API such as viper.IsSet(), which have
broken some of our flags checks. Instead of checking whether
users have changed a flag's default value we should rely on such
defaults and adjust runtime behaviour accordingly. In order to do
so, it's important that we pick sane defaults for all our flags.

The --pruning flag and configuration option now allow for a
fake custom strategy. When users elect custom, then the
pruning-{keep,snapshot}-every options are interpreted and
parsed; else they're ignored.
Zero is pruning-{keep,snapshot}-every default value. When
users choose to set a custom pruning strategy they are
signalling that they want more fine-grainted control, therefore
it's legitimate to expect them to know what they are doing and
enter valid values for both options.

Ref #5964

client/keys/add.go

@@ -190,23 +190,16 @@ func RunAddCmd(cmd *cobra.Command, args []string, kb keyring.Keyring, inBuf *buf
 	coinType := uint32(viper.GetInt(flagCoinType))
 	account := uint32(viper.GetInt(flagAccount))
 	index := uint32(viper.GetInt(flagIndex))
+	hdPath := viper.GetString(flagHDPath)
 
-	useBIP44 := !viper.IsSet(flagHDPath)
-	var hdPath string
-
-	if useBIP44 {
+	if len(hdPath) == 0 {
 		hdPath = hd.CreateHDPath(coinType, account, index).String()
-	} else {
-		hdPath = viper.GetString(flagHDPath)
+	} else if viper.GetBool(flags.FlagUseLedger) {
+		return errors.New("cannot set custom bip32 path with ledger")
 	}
 
 	// If we're using ledger, only thing we need is the path and the bech32 prefix.
 	if viper.GetBool(flags.FlagUseLedger) {
-
-		if !useBIP44 {
-			return errors.New("cannot set custom bip32 path with ledger")
-		}
-
 		bech32PrefixAccAddr := sdk.GetConfig().GetBech32AccountAddrPrefix()
 		info, err := kb.SaveLedgerKey(name, hd.Secp256k1, bech32PrefixAccAddr, coinType, account, index)
 		if err != nil {