ConfirmApplyPlugin - allow message customization

[kmanning]

• Allow it to be enabled/disabled
• Allow the text of the prompts to be overridden

Example:

...
ConfirmApplyPlugin.disable()
...

The human confirmation step for every environment should now go straight from plan to apply, without prompting the user.

Do we care about skipping some environments and not others?

[kmanning]

Acceptance Criteria:

Given	When	Then
I override the confirm message	my pipeline runs	I see the new message asking me to confirm before applying the terraform plan
I override the Ok message	my pipeline runs	I see the new label on the OK button to confirm
I override the submitter	my pipeline runs	(where is this even used...?)

[kmanning]

The disable functionality seems potentially dangerous. Consider separating that into another issue. If we move forward with it, it should get a clear warning about what will happen.

[kmanning]

Removing disable functionality, and pushing it to another Issue #264