Conditional Policy: Add more operations

[davidor]

Right now, the conditional policy only supports 2 operations (!=, ==), and and/or for combining them.

After some discussion in #820 it looks that we'll need to add support for others for the @3scale/ostia project:

• As operations: >=, <=, >, <, starts_with, matches.
• For combining: nand, nor, xor, equals.

[jmprusi]

yup, those improvements should be enough! 👍

[davidor]

The "matches" operation was added in #975

[unleashed]

was it? I see it not merged?

[davidor]

Now it is @unleashed :D

[davidor]

We should also consider operations such as "includes" and "excludes" as suggested by @mikz in #976 (comment)