IDE: Allow environment variable override in ThirdPartyPath, and use it also for matiec.

IDE: re-use eRPC URI definitions in connector factory.

Preparing for serial and US eRPC connection.

Cosmetic changes

IDE: refactor discovery panel / zeroconf

Bundle ZeroConf listener and interfaces changes monitor into separate module.
Prepare to extend with USB device browsing.

IDE: refactor ERPC URI editor, add serial and USB URI types

python runtime: update ServicePublisher to current Zeroconf API

eRPC: Backward compatibility with runtime versions missing GetVersions extended call.

eRPC: Version bump

python_runtime: fix ExtendedCall register/unregistering.

eRPC: Server closes connection on exception to prevent client to block until timeout when it happens.

Add ExtendedCall to PLCObject as a replacement of RemoteExec and reflect it in eRPC interface.

ExtendedCall is a generic remote procedure call that runtime code can register to and that IDE extensions can call.
For example a fieldbus extension can use ExtendedCall to browse the fieldbus devices connected to the runtime.

Removed dependency in requirements.txt.