chore: refactor printers code structure

[howieyuen]

What type of PR is this?

/kind bug

What this PR does / why we need it:

• avoid import cycle

Which issue(s) this PR fixes:

Fixes #

Special notes for your reviewer:

• make Convert() and Generate() public
• avoid import cycle

Does this PR introduce a user-facing change?

NONE

Additional documentation e.g., design docs, usage docs, etc.:

[coveralls]

Pull Request Test Coverage Report for Build 4260336131

• 0 of 1 (0.0%) changed or added relevant line in 1 file are covered.
• 7 unchanged lines in 1 file lost coverage.
• Overall coverage decreased (-0.08%) to 72.349%

---

Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
pkg/engine/operation/watch.go	0	1	0.0%

Files with Coverage Reduction	New Missed Lines	%
pkg/cmd/apply/options.go	7	71.2%

Totals
Change from base Build 4242722717:	-0.08%
Covered Lines:	4681
Relevant Lines:	6470

---

💛 - Coveralls

[liu-hm19]

lgtm