Suggestion: make Parser.parse static

https://github.com/algolia/algolia-filters-js-syntax-validator/blob/6446be2cc325c726cb1450b626a9d1acc5a930fb/src/parser.js#L4

If this would be instead `static parse(s)`, it would be able to be used as:

```js
const Parser = require('algolia-filters-js-syntax-validator');

const response = Parser.parse('A or B');
```

Not exactly necessary of course, but would be simpler IMO

Feel free to close if you think otherwise

Read src/parser.js at the linked line to understand the current Parser.parse entry point and how the module is exported. Verify that the requested static API supports Parser.parse('A or B') while preserving the existing parsing behavior; the issue does not mention a test file to run.

Written by the indexing model from the issue text.