SE-2483 Unhide student-generated certificates toggle

Description

Student-generated certificates are meant to be auto-enabled through
signal for self-paced courses, but it has been observed that this
behaviour is flaky. When this happens, we are left in a state where it
is impossible to enable student-generated certificates because the
section is hidden in the instructor dashboard.

Also by unconditionally displaying the toggle button, this allows more
flexibility for instructors. For example, it may be desirable for
student-generated certificates to be disabled for a self-paced course.

*Dependencies*: None

*Screenshots*:

![1587014540](https://user-images.githubusercontent.com/9714796/79417700-ea1f7f00-7ff1-11ea-8cc8-4ed0702edf11.png)

*Sandbox URL*: TBD - sandbox is being provisioned.

*Merge deadline*: None

*Test instructions*:

1. Create a self-paced course (or change an existing course to be self-paced)
1. visit the instructor dashboard for the self-paced course
1. navigate to the Certificates tab
1. verify that the 'Student-Generated Certificates' section is visible along with the toggle button
1. verify that clicking the toggle button toggles this setting correctly

*Reviewers*:

  • [ ] @pomegranited

  • [ ] edX Reviewers TBD

*Settings*
```yaml

```

Assignee

Marco Morales

Reporter

Open Source Pull Request Bot

Labels

Contributor Name

Samuel Walladge

Repo

edx/edx-platform

Customer

Epic Link

None

OSCM Assignee

None

Platform Map Area (Levels 1 & 2)

Learner Experiences - Credentials

Platform Map Area (Levels 3 & 4)

None

Blended Hour Utilization Percentage

None

Priority

Unset
Configure