Rename boolean operations in FileTest module

[harendra-kumar]

Currently we use <> and and for boolean conjunction, and or for boolean disjunction. I propose the following changes:

• Add .& for conjunction and .| for disjunction. . acts as a mnemonic for composing predicates and &, | indicate the boolean &&, ||.
• Remove/reimplement and and or so that they can be used for conjunction or disjunction of a list of predicates
• Rename neg to not_
• Remove the Semigroup instance so that there is only one way of using conjunction