Add error codes to event api to send error codes to Skaffold Event API

[tejal29]

Fixes: This is an internal work item requested by IDEs to better report failure cause.

Description
This change

1. Adds a ENUM type to skaffold event proto ErrorCode
   This Enum is added to each

• Build,
• Deploy,
• FileSync
• StatusCheckEvent

2. Adds a new errors package at pkg/skaffold/errors with a function ErrorCodeFromError which will responsible to translate an error string to error code.
   Currently this returns error code COULD_NOT_DETERMINE

User facing changes (remove if N/A)
New field for IDEs to consume.

Follow-up Work (remove if N/A)
The follow work will include,

1. Going through all errors in pkg/skaffold/<pkg> e.g. below and converting them to distinct error codes wherever possible.

git grep 'fmt.Errorf' pkg/skaffold/build/jib/
pkg/skaffold/build/jib/sync.go:         return nil, fmt.Errorf("failed to unmarshal jib sync JSON: %w", err)
pkg/skaffold/build/jib/sync.go:         return nil, fmt.Errorf("failed to add jib json direct entries to sync state: %w", err)
pkg/skaffold/build/jib/sync.go:         return nil, fmt.Errorf("failed to add jib json generated entries to sync state: %w", err)

2. Add implementation to ErrorCodeFromError which could be as simple as regex matching.

[codecov]

Codecov Report

Merging #3954 into master will decrease coverage by 0.00%.
The diff coverage is 100.00%.

Impacted Files	Coverage Δ
pkg/skaffold/errors/errors.go	100.00% <100.00%> (ø)
pkg/skaffold/event/event.go	93.05% <100.00%> (+0.10%)	⬆️
...affold/kubernetes/portforward/kubectl_forwarder.go	65.85% <0.00%> (-2.44%)	⬇️