Complete unary operator/expression support

[markandrus]

AFAICT, these unary operators/expressions still lack support:

9.3. Mathematical Functions and Operators

• |/ double precision → double precision
• ||/ double precision → double precision
• @ numeric_type → numeric_type

9.6. Bit String Functions and Operators

• ~ bit → bit

9.11. Geometric Functions and Operators

• @-@ geometric_type → double precision
• @@ geometric_type → point
• # geometric_type → integer
• ?- line → boolean
• ?| line → boolean

9.13. Text Search Functions and Operators

• !! tsquery → tsquery

(Some of these operators appear in other sections of the documentation, but I've only included them once.)