Add ability to deploy Kubernetes application to the specified namespace

[nghialv]

What this PR does / why we need it:

Which issue(s) this PR fixes:

Fixes #

Does this PR introduce a user-facing change?:

NONE

[pipecd-bot]

The following ISSUES will be created once got merged. If you want me to skip creating the issue, you can use /todo skip command.

Details

---

1. Add namespace for generated resources.

https://github.com/pipe-cd/pipe/blob/8a201eab0f14a2d29289b29f01f9395fb78d1b11/pkg/app/piped/executor/kubernetes/canary.go#L141-L144

This was created by todo plugin since "TODO:" was found in 8a201ea when #213 was merged. cc: @nghialv.

[pipecd-bot]

Code coverage for golang is 25.84%. This pull request decreases coverage by -0.03%.

File	Function	Base	Head	Diff
pkg/app/piped/cloudprovider/kubernetes/kubectl.go	Kubectl.Apply	0.00%	0.00%	+0.00%
pkg/app/piped/cloudprovider/kubernetes/kubectl.go	Kubectl.Delete	0.00%	0.00%	+0.00%

[stormcat24]

/apporve

[stormcat24]

/approve

[pipecd-bot]

This pull request is APPROVED by stormcat24.

Approvers can cancel the approval by writing /approve cancel in a comment. Any additional commits also will change this pull request to be not-approved.