Live stream insertion support

[elv-serban]

Support for the new live stream capability - ad/content insertion.

• status reports list of insertions
• new command insertion can be used to add or remove an existing insertion from a live stream (write token)

./elv-stream insertion
 insertion <stream> <time> <duration> <target_hash>

Pauses the currently active live stream.

Positionals:
  stream       Stream name or QID (content ID)               [string] [required]
  time         Insertion time relative to stream start (seconds with 6 decimal
               precision)                                             [required]
  duration     Duration (seconds with 6 decimal precision)            [required]
  target_hash  Target content object hash (playable)         [string] [required]

Options:
      --version  Show version number                                   [boolean]
  -v, --verbose  Verbose mode                                          [boolean]
      --help     Show help                                             [boolean]
      --remove   Flag indicating the insertion is to be deleted```

[elv-michelle]

time is with respect to start of the stream?

The constant abr duration will presumably be read / determined from the content rather than hard coded, right?

This is AWESOME!!