Fixes and changes for /mentors/requests and /admin/apps

[prog-z-99]

General changes

• General error fixes (SVG, table, div-related HTML/React error messages)

/mentors/requests changes

• Fully changed remarks field with comments field (#11)
• Request are now fetched partially on initial fetch, details are fetched as-needed (#10)
• Simplified fetch order

/admin/apps changes

• Comments now properly show up + N/A text is actually there
• apps can now be denied correctly (whoops)
• Unnecessary code removed

[prog-z-99]

LGTM

@fishcodeslol