feat: Support calling a function to get the config

[Jason3S]

With the release of v8.3.0 it will be possible to return a function from cspell.config.js files. This function will be called to get the configuration. It can return a Config Object or Promise that resolves to a Config Object.

Example:

cspell.config.mjs

import { readFile } from 'node:fs/promises';

/**
 * @returns {Promise<import('@cspell/cspell-types').CSpellUserSettings>}
 */
export default async function getConfig() {
    const words = (await readFile(new URL('requirements.txt', import.meta.url), 'utf8'))
        .replace(/[.,]|([=<>].*)/g, ' ')
        .split(/\s+/g);
    return { id: 'python-imports', words };
}