feat: Support app-wide update-strategy annotations

[janpieper]

Problem

Currently, you're forced to specify e.g the update strategy per image, although it might be the same for all:

# ...
metadata:
  annotations:
    argocd-image-updater.argoproj.io/image-list: frontend=my-fancy-frontend, backend=my-fancy-backend
    argocd-image-updater.argoproj.io/frontend.update-strategy: name
    argocd-image-updater.argoproj.io/backend.update-strategy: name
# ...

Proposal

This PR adds four new annotations to allow you to specify update-strategy related options for all images in a ArgoCD application.

• argocd-image-updater.argoproj.io/allow-tags
• argocd-image-updater.argoproj.io/ignore-tags
• argocd-image-updater.argoproj.io/force-update
• argocd-image-updater.argoproj.io/update-strategy
• argocd-image-updater.argoproj.io/pull-secret

_{(Note: I am using the update-strategy annotations for all of my following examples, but the handling is the same of all of them)}

With these new annotations you can use only one annotations to specify it for all of them:

# ...
metadata:
  annotations:
    argocd-image-updater.argoproj.io/image-list: frontend=my-fancy-frontend, backend=my-fancy-backend
    argocd-image-updater.argoproj.io/update-strategy: name
# ...

You can still override the app-wide configuration by adding the image-based annotation:

# ...
metadata:
  annotations:
    argocd-image-updater.argoproj.io/image-list: frontend=my-fancy-frontend, backend=my-fancy-backend
    argocd-image-updater.argoproj.io/update-strategy: name
    argocd-image-updater.argoproj.io/frontend.update-strategy: semver
# ...

Order

When configuring these annotations, that's the order of how the options get evaluated:

#	Annotation	Description
1	argocd-image-updater.argoproj.io/<alias>.<option>	for specific image
2	argocd-image-updater.argoproj.io/update-strategy	for all images (app-wide)
3	-/-	default

Additional changes

• Renamed SecretListAnnotation to PullSecretAnnotation
• Renamed ApplicationWideSecretListAnnotation to ApplicationWidePullSecretAnnotation

[jannfis]

Hi @janpieper - will you have time to finish this PR?

I'm asking because I really would like to include this feature with v0.12.0, which is most likely going to be released early February.

[janpieper]

Will try to get this done by the end of the week 😉 Don't know whether I find some time before the weekend, but let's see 😉

[janpieper]

@jannfis I think (hope?) the changes should be complete for the proposed new feature, so I mark this PR ready for review 😉

I did not include all your changes from your closed PR, to not blow up this PR with "unrelated" changes.

[jannfis]

Thanks a lot for this contribution, @janpieper! Much appreciated.

Change LGTM.