feat: Prefill business trip allowances and whole day times

[0xD0M1M0]

• Prefills the allowances table with the to/from dates selected as travel range.
• Sets the hidden time fields for whole days so for e.g. the print out show the correct times in the tables
• Introduces business trip settings
• Allows to input distances for private cars for mileage calculations
• Links purchase invoices with business trips
• Auto creates purchase invoices with pre-set (see business trip settings) suppliers, items and expense accounts if a receipt is attached to the specific line. Purchase invoice only recieves the copied receipt, but full data needs to be completed in the purchase invoice

[0xD0M1M0]

This PR is ready for review.