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### Why is this Change Important & Necessary?
Partially addresses [Issue #10273 In
Submitty/Submitty](Submitty/Submitty#10273)

### What is the New Behavior?
The leftmost 4 rows, which contain the User ID, Numeric ID, First Name,
& Last Name, stay in place when scrolling to the right.

Before:


https://github.com/user-attachments/assets/35260e4f-8a84-482f-b9b5-422e95516b5a


After:


https://github.com/user-attachments/assets/3d761ea3-1ab3-4047-a671-09c0b81219fd

### What steps should a reviewer take to reproduce or test the bug or
new feature?

1. As an instructor, visit the grades configuration tab and rebuild the
rainbow grades.
2. Visit the gradebook page and try scrolling the table of grades left
and right.
3. Observe the new behavior or sticky columns.

Edit: Since multiple people noted issues with testing this PR due to the
changes existing in two different repositories, here are instructions
for setting up Submitty to read the changes in the RainbowGrades
repository.

1. run `git clone https://github.com/Submitty/RainbowGrades.git` in the
directory above Submitty. The resulting file structure should look like:
```
RCOS_Submitty/ (or some other name)
├─ Submitty/
│  ├─ site/
│  ├─ grading/
│  ├─ bin/
│  ├─ ...
├─ RainbowGrades/
│  ├─ student.cpp
│  ├─ table.cpp
│  ├─ output.cpp
│  ├─ ...
├─ ...
```
2. in the RainbowGrades folder, run `git checkout sticky-columns`
3. in the Submitty folder, run `git checkout gradebook-format-fix`
4. in the Submitty folder, run `vagrant halt`, then `vagrant up`, to
link the RainbowGrades folder to the VM. If this worked correctly you
should see the line
`ubuntu-22.04: /home/username_example/RCOS_Submitty/RainbowGrades =>
/usr/local/submitty/GIT_CHECKOUT/RainbowGrades`
5. run `vagrant ssh`, the run `submitty_install`, to fetch re-compile
rainbow grades.
6. follow the build and test instructions listed above.

### Automated Testing & Documentation
No testing or documentation is needed, as the change is purely visual.

### Other information
Due to a small styling issue, I had to make a 1-line PR in the
Submitty/Submitty repository, which can be found
[here](Submitty/Submitty#12754). Reviewers
should review both PR's simultaneously.