feat: add support for --config option in push command

[vigneshshanmugam]

• Add support for Push command that was not handling the --config option correctly. This PR fixed that and allows users to push the same journeys under different projects using different configuration file.

> npx @elastic/synthetics push --config <synthetics.config.prod.ts>

> npx @elastic/synthetics push --config <synthetics.config.qa.ts>

[devcorpio]

LGTM

Testing setup

relevant content of my synthetics.config.ts file:

    monitor: {
      schedule: 5,
      locations: ['dev'] as any,
      privateLocations: [],
      tags: ['']
    },
    /**
     * Project monitors settings
     */
    project: {
      id: 'testear',
      url: 'http://kibana-server:5601/zpf/',
      space: 'default',

    },

relevant content of a new file named synthetics.config.devcorpio.ts file:

    /**
     * Configure global monitor settings
     */
    monitor: {
      schedule: 60,
      locations: ['dev'] as any,
      privateLocations: [],
      tags: ['devcorpio-test']
    },
    /**
     * Project monitors settings
     */
    project: {
      id: 'testear-devcorpio-test',
      url: 'http://kibana-server:5601/zpf/',
      space: 'default',
    },

Testing flow (npm users, don't forget to set the extra "--" when passing flags)

Execute the command: "npm run push -- --config synthetics.config.devcorpio.ts"

• The results of executing that command in a branch WITHOUT the changes show:

We can see how schedule and project-id values are not taken from config.devcorpio.ts, as expected.

• The results of executing that command in the branch of this PR shows the values of the new file:

🎉

• If I execute the push command without setting --config, it takes the default one 👍

[gsantoro]

I tested this and it works as expected.

I can push the same set of journeys (the same files) with two different configs for two different projects.

The two different push commands won't interfere with each other, and all parameters from the config files will be used correctly.