LIMS-2044: Remove luxon

[ndg63276]

JIRA ticket: LIMS-2044

Summary:

Remove the luxon library.

Changes:

• Remove luxon from package.json and package-lock.json
• Convert calendar functions to native JS
• Use native JS and don't worry about time zones when calculating length of visits (this would seem to mostly apply to creating visits in Synchweb, which we don't do, but the code is called by various pages)
• Fix a rogue missing comma I found
• Add a new linting rule as we are ignoring it anyway

To test:

• View the list of visits for a proposal, check no errors occur
• View the data collection page, check no errors occur
• View the calendar page, check no errors, check days of the week, check days in the month etc.
• (Dev DB only) Go to the 'Add New Visit' page at eg /admin/proposals/visit/add/mx23694, check you can add a new visit

[gfrn]

Any chance we can remove Luxon altogether? Seems like it's being used in only 2 places