refactor(config): merge 2 separate YAML editor pages into one

[AnsonH]

Description

Currently the YAML config editor page is present into two pages:

• Create new assignment: /assignments/{assignmentId}/configs/new
• Edit existing assignment: /assignments/{assignmentId}/configs/{assignmentConfigId}/yaml

Both pages are very similar except for a few additional features in the "Edit existing assignment" page. Instead of splitting up the code for the two pages into two separate files, we should merge the code into a single file. This avoids code duplication.

Solutions

• Investigate /assignments/{assignmentId}/configs/{assignmentId}/yaml, where assignmentConfigId has a type of number | "new"

Screenshots

/assignments/{assignmentId}/configs/new

/assignments/{assignmentId}/configs/{assignmentConfigId}/yaml

[AnsonH]

This will not be done within the scope of this FYP since Kris is interested in revamping the entire ZINC UI. This issue would remain open for future maintainers to be aware that they can merge two separate pages into a single one.