Compensation calculator UI updates

Addresses the following UI updates from #853 (closed)

• Change level dropdown to be before experience
• Deep link to calculator where it says How does our calculator work
• Remove link to contracts page, it's confusing... add that link back to the handbook page instead
• Remove the sentence about paying in local currency
• Change title from Your compensation to Compensation
• Add direct link to calculator
• Add Apply header for apply section in all job pages
• Changed experience input from singular to ranged
• Add note about annual compensation
• Add link to stock options and benefits
• Hide contract type information on first load
• Remove link explaining contract types
• Add link to contracts page in compensation handbook
• Replaces contract type factor list with table in compensation handbook
• Add sources of inspiration for salary calculator (@ernstvn)