Is your feature request related to a problem? Please describe.

P0 - make sure KubeVela support all features from this repo, and keep this repo as is (i.e. supports OAM spec v0.2.1 only).

For more detail about why we made above decision, please check the README of oam-kubernetes-runtime.

TL;DR, we have decided to promote OAM Kubernetes Runtime to an end-to-end app platform engine with the name of KubeVela. Please check its documentation site to learn about using OAM (Open Application Model) with Kubernetes in detail.

Describe the solution you'd like

Task list:

1. Add a --spec=v0.2.1 to kubevela installation config. When it is set, OAM spec release v0.2.1 crds will be installed instead of latest release.
2. Ensure in v0.2.1 mode, all features and examples in this repo work in KubeVela, add e2e test in KubeVela to verify it.
3. Add a doc in KubeVela about how to use it in v0.2.1 mode, with sample/examples.
4. (Optional) Add a doc to teach users how to upgrade from v0.2.1 to latest release.

Describe alternatives you've considered

Additional context