ci: adds basic setup

[codefromthecrypt]

What type of PR is this?

/kind cleanup

What this PR does / why we need it:

This sets up basic CI with a couple notable targets:

• make check: runs various linters and formatters, and ensures projects build.
• make test-scheduler: runs scheduler-based unit and e2e tests.

Which issue(s) this PR fixes:

None

Special notes for your reviewer:

Later, we can make tests that run in tinygo for the guest, but as that's tricky I left things here for now.

Does this PR introduce a user-facing change?

NONE

What are the benchmark results of this change?

N/A

[codefromthecrypt]

rebased. I'm not sure if actions are disabled on this repo, but most of the change only helps if they are.

[codefromthecrypt]

rebased. main thing left in here is lint fix, fix of tinygo go.mod, and basic CI plumbing

[codefromthecrypt]

thanks @anuraaga I wove in the feedback and preemptively squashed as usually asked to and doing that loses approvals.

[kerthcet]

/approve

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: anuraaga, codefromthecrypt, kerthcet

The full list of commands accepted by this bot can be found here.

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Needs approval from an approver in each of these files: - ~~[OWNERS](https://github.com/kubernetes-sigs/kube-scheduler-wasm-extension/blob/main/OWNERS)~~ [kerthcet] Approvers can indicate their approval by writing `/approve` in a comment Approvers can cancel approval by writing `/approve cancel` in a comment

[codefromthecrypt]

Thanks for the help getting this together @anuraaga and thanks for being open to trying non-standard CI @kerthcet!