feat: add workspace cli

[healthjyk]

What type of PR is this?

/kind feature

What this PR does / why we need it:

add workspace cli

Which issue(s) this PR fixes:

Fixes #604

[coveralls]

Pull Request Test Coverage Report for Build 7320679901

• 275 of 323 (85.14%) changed or added relevant lines in 14 files are covered.
• 3 unchanged lines in 1 file lost coverage.
• Overall coverage increased (+0.3%) to 74.99%

---

Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
pkg/workspace/util.go	0	1	0.0%
pkg/cmd/workspace/cmd.go	24	26	92.31%
pkg/cmd/workspace/create/cmd.go	28	30	93.33%
pkg/cmd/workspace/del/cmd.go	27	29	93.1%
pkg/cmd/workspace/del/options.go	19	21	90.48%
pkg/cmd/workspace/show/cmd.go	27	29	93.1%
pkg/cmd/workspace/update/cmd.go	29	31	93.55%
pkg/cmd/workspace/create/options.go	24	28	85.71%
pkg/cmd/workspace/show/options.go	22	26	84.62%
pkg/cmd/workspace/update/options.go	24	28	85.71%

Files with Coverage Reduction	New Missed Lines	%
pkg/engine/operation/parser/parser.go	3	79.27%

Totals
Change from base Build 7320192927:	0.3%
Covered Lines:	7616
Relevant Lines:	10156

---

💛 - Coveralls

[liu-hm19]

lgtm