config: correctly print byte and array types on get

When getting config values of type bytes or list (technically a protobuf
repeated container type), these were directly printed on the output.
However, the retrieved values could not be set by --set again, as the
format was different (e.g. python string representation of bytes vs.
base64 prefixed and encoded as expected by --set).

We fix this by adding a toStr utility function (similar to the fromStr)
function to convert byte types correctly to the base64 representation.
Further, we check if the type is repeated and apply this operation to
all values.

meshtastic/util.py

@@ -100,6 +100,13 @@ def fromStr(valstr):
     return val
 
 
+def toStr(raw_value):
+    """Convert a value to a string that can be used in a config file"""
+    if isinstance(raw_value, bytes):
+        return "base64:" + base64.b64encode(raw_value).decode("utf-8")
+    return str(raw_value)
+
+
 def pskToString(psk: bytes):
     """Given an array of PSK bytes, decode them into a human readable (but privacy protecting) string"""
     if len(psk) == 0: