TNL-4356

Allows multiple bulk email targets to be specified at once.

-The previous "All" option has been split into "Staff" and "Learners"
-The backend changes made here lay the groundwork for cohort emailing
-The data migration, 0005, is somewhat large and requires deploy attention
-Tests have been updated
-Numerous safe-commit-linter fixes are included

- added the abstract and concrete layers of enrollment report provider
- created a celery task.
-added the button in the e-commerce reports section

added the enrollment data backend

added the payment data and start writing the test cases.

updated the code with the feedback suggestions and wrote some test cases.
- all the downloadable reports are now visible in the ecommerce download section.
Pending instructor tasks is also visible in the ecommerce section

added the fields in the user profile information
changed the report store configuration key
added the new http endpoint for financial reports to add more permissions for finance_admin to access.

fix quality issues

added test cases to check csv content data

rebased with master and resolved conflicts

changed the log messages

added the changes as per code clintonb suggestions during code review

updated the test cases for the finance_admin decorator

changes suggested by clinton.

Created and moved Table level filters to the Custom Manager for the CourseEnrollment model.

ecommerce.js file was loaded twice in the instructor_dashboard.js fixed the issues

added the registration code column in the csv

added the full gender in the csv file

Update data sources and add display name translations for the report columns

fix meta name

Make sure the reports section does not appear on non whitelabel courses

pylint fixes

expand out enumerated values

Conflicts:
	lms/djangoapps/courseware/courses.py
	lms/djangoapps/instructor_task/api.py

refined entrance exam student attempts reset
added rescore, delete state and task history functionality

This commit pulls in changes from #4487 that implements keyword
substitution for bulk emails. With these changes, an instructor can
include keywords in their bulk emails which will be automatically substituted
with the corresponding value for the recepient of the email. Keywords are
of the form %%keyword%%, and the keywords implemented in this commit include:

%%USER_ID%% => anonymous_user_id
%%USER_FULLNAME%% => user profile name
%%COURSE_DISPLAY_NAME%% => display name of the course
%%COURSE_END_DATE%% => end date of the course

Client-side validations have also been implemented to ensure that only emails
with well-formed keywords can be sent.
The architecture is designed such that adding in new keywords in the future
would be relatively straight-forward.

This commit adds a message to the instructor dashboard that is displayed when
no instructor tasks are currently running. This message is displayed where the
instructor pending tasks table would normally be placed, and is replaced
with the table when there are running tasks.

This addresses a bug in the email content history table where
"Unknown" was displayed in the number of emails sent column if any sort of
failure occurred during email sending. This behavior has been editted so now
the number of emails that failed to send is displayed, along with the number
of emails that were successfully sent. If the email task is still pending,
"0 sent" is displayed.

As a small addition, the table now also includes the authors of previously
sent emails, and the modal window for an email also displays its author.

Previously on the send email page of the instructor dashboard, instructors could only view
task information about emails they've sent for their course in the past.
In addition to this, I've now added the ability to see the content of all previously sent emails.

A "Sent Email History" button has been added to the page. When clicked, a table displaying the
subject line, number of emails sent, and date/time of submission for each previously sent email
is created. An instructor can then click on any subject line to see the content of that email,
displayed in a modal window that appears on the page.

The window is also equipped with a "copy email to editor" button, which copies the emails contents
to the tinyMCE editor, so that an instructor can easily resend an email that they've sent
in the past.

LMS-2357

Restrict grade report generation to 'is_superuser' users (can be overridden with
feature flag ALLOW_COURSE_STAFF_GRADE_DOWNLOADS); all staff users can download
generated files.

LMS-58

LMS-1244

Respond to review comments

LMS-1242

Add testing coverage
LMS-1242

Add "Edit This Course In Studio" link for studio courses
LMS-1291

Add Pending Tasks section to the following tabs:
* Course Info
* Student Email
* Data Download
* Email

LMS-1242