feat(cron): Added timezone support to cron workflows. Closes #1931

[simster7]

Closes: #1931

Checklist:

• Either (a) I've created an enhancement proposal and discussed it with the community, (b) this is a bug fix, or (c) this is a chore.
• The title of the PR is (a) conventional, (b) states what changed, and (c) suffixes the related issues number. E.g. "fix(controller): Updates such and such. Fixes #1234".
• I have written unit and/or e2e tests for my change. PRs without these are unlike to be merged.
• Optional. I've added My organization is added to the README.
• I've signed the CLA and required builds are green.

[codecov]

Codecov Report

Merging #1986 into master will decrease coverage by 0.01%.
The diff coverage is 0%.

@@            Coverage Diff            @@
##           master   #1986      +/-   ##
=========================================
- Coverage    8.88%   8.87%   -0.02%     
=========================================
  Files          53      53              
  Lines       33608   33647      +39     
=========================================
  Hits         2985    2985              
- Misses      30233   30272      +39     
  Partials      390     390

Impacted Files	Coverage Δ
pkg/apis/workflow/v1alpha1/openapi_generated.go	0% <0%> (ø)	⬆️
pkg/apis/workflow/v1alpha1/generated.pb.go	0.45% <0%> (-0.01%)	⬇️

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[alexec]

Conditional approval, conditions:

1. Please can you make it clear to users what the default is.
2. This is consistent with K8S Crons as per https://kubernetes.io/docs/concepts/workloads/controllers/cron-jobs/