Moved "Install Assessment" button to top box, removed "Instructor Actions" header, renamed Assignments header to Assessments

[KesterTan]

Description

• Moved "Install Assessment" button to top box
• Removed "Instructor Actions" header
• Renames Assignments header to Assessments
• Assessments header will only be shown if there are assessments
• Added icon to assignments

Motivation and Context

Small UI fix because instructor actions is unnecessary as its own component and assessments is also unnecessary as a header if it is empty.

How Has This Been Tested?

1. Tested mobile responsiveness.
2. Tested the buttons and other buttons.

Previous:

After:

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• I have run rubocop for style check. If you haven't, run overcommit --install && overcommit --sign to use pre-commit hook for linting
• My change requires a change to the documentation, which is located at Autolab Docs
• I have updated the documentation accordingly, included in this PR

[damianhxy]

Could we get an icon for the install assessment button to match the aesthetic of the other buttons?

You can find the list of icons here: https://materializecss.com/icons.html

For example,

<%= link_to "<i class='material-icons left'>input</i>Install Assessment".html_safe, ...

[damianhxy]

LGTM

Would like to see an icon for the install assessments button, though

[damianhxy]

Icon looks good

[damianhxy]

Would prefer to revert the button name to "Install Assessment" (singular), and also restore the trailing newline

[KesterTan]

Added newline and changed assessments to assessment

[najclark]

lgtm, nice job!

[damianhxy]

LGTM