Delete workspace

[paulovmr]

Implement delete workspace action, with a confirmation popup prompting the user to type the name of the workspace to confirm.

[YosiElias]

/assign

[YosiElias]

Done by #178

[YosiElias]

/close

[google-oss-prow]

@YosiElias: Closing this issue.

In response to this:

/close

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