Improve and freeze P-vector reports

[redeboer]

Some left-overs from the todo-list of ComPWA/compwa.github.io#278.

### To do
- [ ] Explain code, particularly `DynamicsSymbolBuilder`
- [ ] Change color cycle?
- [ ] Render fit process with `CSVSummary`
- [ ] Widget for starting parameters
- [ ] Parametrize Breit-Wigner with coupling g as well
- [ ] Test coupled fit with resonance mass between threshold
- [ ] Remove i from phase space factor
- [ ] Freeze **TR-030**, **TR-031**, and **TR-032**
- [ ] Improve ratios Argand plots
- [ ] Fix title of **TR-032** (coupled channel fit)
- [ ] Generalize **TR-032** so it can handle multiple poles