refactor(update): clean up actions/update

[piksel]

This PR tries to refactor the update code flow to make it easier to understand, maintain and extend.

actions/update:

• move common arguments to a shared struct (updateSession)
• remove unused fields
• fix outdated names
• improve logging/error handling

lifecycle:

• removes unwieldy SkipUpdate return value in favor of errors.Is
• generalizes the code for all four phases
• allows timeout to be defined for all phases
• enables explicit unit in timeout label values (in addition to implicit minutes)

container:

• rename Stale to MarkedForUpdate renames the container.Stale field to what it's actually used for, as staleness is not the only factor used to decide whether a container should be updated anymore

[codecov[bot]]

Codecov Report

Attention: 67 lines in your changes are missing coverage. Please review.

Comparison is base (76f9cea) 70.55% compared to head (a42eb28) 69.97%.

Files	Patch %	Lines
internal/actions/update.go	64.04%	18 Missing and 14 partials :warning:
pkg/container/metadata.go	48.27%	13 Missing and 2 partials :warning:
pkg/container/client.go	42.85%	8 Missing :warning:
pkg/container/container.go	0.00%	7 Missing :warning:
internal/util/time.go	0.00%	5 Missing :warning:

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1895      +/-   ##
==========================================
- Coverage   70.55%   69.97%   -0.59%     
==========================================
  Files          26       27       +1     
  Lines        2493     2498       +5     
==========================================
- Hits         1759     1748      -11     
- Misses        633      648      +15     
- Partials      101      102       +1     

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[pjdubya]

Hi @piksel . Just curious if there was any movement on this PR? Would love to update my other PR for deferred updates to match this code and get that resolved too whenever you're ready. LMK if there's anything else I can do to help here!

[minscof]

It would be nice to finish this work

[MattBlackOnly]

@piksel would also be interested in this too for defer functionality