Asset (minus return/convert and bulk uploads)

[nesh170]

• get all assets
• update assets
• update item => does not allow to be converted to non-asset if asset. cannot change quantity of asset
• sendCart for admin => error-handling if loan/disbursment does not contain asset
• delete asset => auto decrements item quantity
• create asset => increment item quantity
• log acquisition and destruction => does not allow modification if assets
• full return of loans
• custom fields for assets

Still needs to be done:

• partial return of loans for assets
• conversion between disbursement and loans for assets
• bulk uploads

[nesh170]

@ankitkayastha lololol actually tbh rip life