Add chart building + ensure BINDIR is created when running targets

[SgtCoDFish]

1. Adds make chart to generate a local helm chart for testing
2. Creates $(BINDIR) and subdirectories using order only dependencies (see details in the cert-manager repo)
3. Use $@ where possible
4. Adds release version as a variable since it's now used in more than one place

I'd probably also advocate changing $(BINDIR) to default to _bin for the same reasons we did that in cert-manager but that seemed maybe a change too far for this PR

[jetstack-bot]

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[SgtCoDFish]

/test pull-cert-manager-trust-smoke

[JoshVanL]

Small thing from me 🙂

[SgtCoDFish]

/test pull-cert-manager-trust-verify
/test pull-cert-manager-trust-smoke

[SgtCoDFish]

�[91mfatal: not a git repository (or any of the parent directories): .git

Ah that's really annoying; I'll have to remove the $(RELEASE_VERSION) stuff, don't want to get into touching the docker build ATM

[SgtCoDFish]

/test pull-cert-manager-trust-smoke

[SgtCoDFish]

/test pull-cert-manager-trust-smoke

[SgtCoDFish]

Smoke test failures were legit, hopefully fixed now 😁

[SgtCoDFish]

/test pull-cert-manager-trust-verify

Comments addressed

[JoshVanL]

/lgtm