feat: auto create namespace

[mayzhang2000]

Checklist:

• Either (a) I've created an enhancement proposal and discussed it with the community, (b) this is a bug fix, or (c) this does not need to be in the release notes.
• The title of the PR states what changed and the related issues number (used for the release note).
• I've updated both the CLI and UI to expose my feature, or I plan to submit a second PR with them.
• Optional. My organization is added to USERS.md.
• I've signed the CLA and my build is green (troubleshooting builds).

[codecov-commenter]

Codecov Report

Merging #3976 into master will increase coverage by 0.01%.
The diff coverage is 33.33%.

@@            Coverage Diff             @@
##           master    #3976      +/-   ##
==========================================
+ Coverage   42.11%   42.12%   +0.01%     
==========================================
  Files         123      123              
  Lines       18127    18132       +5     
==========================================
+ Hits         7634     7639       +5     
  Misses       9514     9514              
  Partials      979      979              

Impacted Files	Coverage Δ
controller/cache/cache.go	0.00% <0.00%> (ø)
controller/sync.go	40.56% <ø> (ø)
controller/appcontroller.go	45.54% <100.00%> (ø)
util/helm/client.go	59.05% <0.00%> (+1.67%)	⬆️

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[alexmt]

LGTM. Can you please include fix in the engine related to namespace creation in the same PR? Just in case someone uses master and decided to try that feature.

[alexmt]

LGTM

[mayzhang2000]

fixed #1809

[konokimo]

I think this feature is great. One thing is Namespace annotations, for istio-injection for example. That is where I see this feature getting to be a bunch of work or not as useful as it seems to be.