Integrate usage of Splunkbase API

[edro15]

This is to keep deployment.yml user-friendly and to the bare minimum by automating fetching of specific splunkbase apps data.

Edit splunkbase-apps format in deployment.yml:

• The app name should match the app title, which is the one shown in Splunkbase (e.g. "TA for Tenable" would become "Tenable Add-On for Splunk" as per Splunkbase)
• Remove app_id and license

# `deployment.yml` example
target:
  url: <your URL>
apps:
  Splunk_TA_app1:
    s3-bucket: splunk-apps-deployment
    source: apps/Splunk_TA_app1.tgz
    config:
      - ./Splunk_TA_app1/*.conf
splunkbase-apps:
  Tenable Add-On for Splunk:
    version: 7.0.0
  Splunk Add on for Microsoft Azure:
    version: 4.2.0

Modify deploy.py to:

• Extract uid (or appid), license and eventually appid (or app_name) via Splunkbase API

# Example to get data for the Tenable TA"
curl --location --request GET 'https://splunkbase.splunk.com/api/v1/app?limit=1&query=%22Tenable%20Add-On%20for%20Splunk%22'

Update documentation accordingly