Dynamic introspection - introduce possibility to add and/or remove interfaces after a Node is being attached

[rgallor]

Introduce two rpc to the MessageHub service: AddInterfaces and RemoveInterfaces, each receiving a list of JSON interfaces as input. The idea is to pass the list of interfaces to add/remove after a Node has been attached to the Message Hub. In particular, if the list of interfaces to add/remove is empty, no operation will be performed, otherwise for each interface the message hub will check which one should be added/removed. The Message Hub should "skip" the interfaces that have already been added or removed (hence, not found).

Close #8

[harlem88]

Add the rust & python code, generated from the latest changes of the proto files.
For the code generation you can follow the README file.

[joshuachp]

I believe a better interface will be to have string for the InterfaceJson since:

• in python we string encode() the interfaces which will write them as UTF-8¹
• Rust strings are already checked to be UTF-8, so this will remove some "error" checks while marshaling the Vec<u8> of the interfaces

Footnotes

1. https://docs.python.org/3/library/stdtypes.html#str.encode ↩

[harlem88]

I believe a better interface will be to have string for the InterfaceJson since:

• in python we string encode() the interfaces which will write them as UTF-81
• Rust strings are already checked to be UTF-8, so this will remove some "error" checks while marshaling the Vec<u8> of the interfaces

Footnotes

1. https://docs.python.org/3/library/stdtypes.html#str.encode ↩

JSON
While the specifications do not constrain the character encoding of the Unicode characters in a JSON text, the vast majority of implementations assume UTF-8 encoding; for interoperability, applications should always and only encode JSON messages in UTF-8.

So I believe we can switch to use String.