Reduce the size of the binary

[vdemeester]

As of today, tkn is a very big binary.

$ du bin/tkn
147M	bin/tkn
$ strip bin/tkn
$ du bin/tkn
118M	bin/tkn

We should try to find some ways to reduce the size of it somehow 👼🏼 🙏🏼. Some ideas:

• Track tektoncd/pipeline deps and understand where we can limit pulling k8s.io ones
• Have our own "struct" representing the types ? (generated)