Add web tests

[cakecatz]

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]

Code coverage for golang is 25.94%. This pull request does not change code coverage.

[pipecd-bot]

Code coverage for javascript is 69.00%. This pull request increases coverage by 1.20%.

File	Base	Head	Diff
src/components/approval-stage.tsx	55.56%	100.00%	+44.44%
src/components/deployment-status-icon.tsx	71.43%	100.00%	+28.57%
src/utils/use-interval.ts	66.67%	100.00%	+33.33%

[nghialv]

Thank you.
/approve

[pipecd-bot]

This pull request is APPROVED by nghialv.

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.