Reseller role and invoice UI improvements

✨ New features

Added reseller role with the ability to:
- View location details
- View credit status details
- Access garage admin areas via user impersonation
- Update job sheet statuses (single or multiple depending on workflow settings)
- Optionally add reseller support contact information (phone/email) to display to garages on their "contact support" page
Reseller details will be marked as "Business" with the Simple GMS team info as "Technical".
Garage reseller support interaction is tracked in Google Tag Manager.

New, lower-priced "lite" version of the system.
- See https://www.simplegms.com/pricing for full details of each system pricing tier.
Location switching tool has been moved to the main sidebar navigation menu.
- Now includes an inline search for users with access to 8+ locations.
Default credit status values have been updated.
Invoices have been updated to better cater for zero-priced items/invoice totals.
Additional report control options and improved UI on the task board, daily report, and end of day invoice report.
Quick invoice selected job type will now be remembered (i.e. "Vehicle + customer" or "Vehicle only").
New features/improvements suggestion page ("Feature suggestions") now linked in the "Contact support" page.

Speed improvements for deciphering theme data (default theme only).
Refined Google Tag Manager integration.
Visual improvements to the check-in app to better fit smaller screen sizes.
Responsive improvements catered for mobile devices.
Additional customer import debug information to determine any file formatting errors.
Fixed issue wherein jobs with a line item not containing a price would error on the job info modal pop-up.
Fixed issue wherein selected location would reset after a period of extended inactivity for multi-location users.
Fixed issue wherein job tooltip would remain visible on calendar week view following modal display.