[Epic] Improve devfile spec support in odo

[kadel]

odo, currently has only limited coverage of devfile specification. We have identified a few areas where we should improve devfile coverage in odo. Most of the requested improvements are based on real scenarios where a lack of support for particular odo features made it hard or impossible to use odo with project.

• [ ] https://github.com/redhat-developer/odo/issues/5821
• [ ] https://github.com/redhat-developer/odo/issues/5701
• [x] https://github.com/redhat-developer/odo/issues/5450
• [x] https://github.com/redhat-developer/odo/issues/5054
• [x] https://github.com/redhat-developer/odo/issues/5832
• [ ] https://github.com/redhat-developer/odo/issues/5706
• [ ] https://github.com/redhat-developer/odo/issues/3577