Enhance support of Browsertrix Crawler arguments

[benoit74]

Fix #416
Fix #433

• Add many missing Browsertrix Crawler arguments
• Drop default overrides by zimit
• Drop --noMobileDevice setting (not needed anymore)
• Document all Browsertrix Crawler default arguments values
• Switch to preferred Browsertrix Crawler argument names
• Fix confusion between Browsertrix stats filename and zimit stats filename + add support for warc2zim stats special location
• Fix support of seeds being sourced from a URL (they were not properly passed to warc2zim)
• Add support for --seedFile being a URL instead of a local file
• Fix confusing variable / function names around arguments
  • zimit_args are not args for zimit but for the crawler or shared, hence better named known_args
  • get_node_cmd_line => get_crawler_cmd_line (crawler is indeed in node, but who cares?)

Due to multiple breaking changes, this will require a major version
Probably better to review commit by commit.

[rgaudin]

LGTM but please check my comments first