feat: enable property in pre-request scripting [INS-3379]

[ihexxa]

Changes:

• enable property in pre-request scripting
• merge similar pre-request script test cases into one to improve performance

How to test:

Run following script:

const { Property, PropertyList } = require('insomnia-collection');

const p1 = new Property('p1');
const p2 = new Property('p2');

const propertyList = new PropertyList(Property, undefined, [p1]);
propertyList.add(p2)

console.log(p1);
console.log(propertyList.all());