Pyxtuml

Improvements and fixes to population of `Label` attribute for Body (`ACT_ACT`) instances during pre-build:
- Set `Label` attribute for bridges and interface signals
- Include state machine type in state and transition action labels
- Change transition label to include start state (or "Non Existent" for creation transitions), event, and destination state

Improvements and fixes to population of `Label` attribute for Body (`ACT_ACT`) instances during pre-build:
- Set `Label` attribute for bridges and interface signals
- Include state machine type in state and transition action labels
- Change transition label to include start state (or "Non Existent" for creation transitions), event, and destination state

- Schema gen improvements
- BridgePoint pre-build
- Support constant values with qualified package names
- Improve pre-build error reporting
- Fix bug with parsing derived attributes located outside a component definition
- Update schema to be compatible with BridgePoint 7.1.0
- Update CI/CD to use GitHub actions

- support loading bridgepoint models from zip archives
- fix a number of compatability issues in the bridgepoint prebuilder
- update bridgepoint metamodel to version 6.16
- add support for set operators to the bridgepoint prebuilder