feat(CMCD): Add CMCD version 2 response mode

[juanmanuel-qualabs]

This PR focuses on the implementation of Response Mode functionalities for version 2 of the Common Media Client Data (CMCD v2) specification within the Shaka Player project.

Key changes made in this pull request include:

• Response Mode: CMCD v2 introduces "Request Mode," "Response Mode," and "Event Mode". Request Mode aligns with the default delivery mode in CMCD v1. Response Mode, which this PR implements, allows clients to send data to one or more alternative destinations after receiving either a full response or an error to a media object request. These reports use one of the defined data transmission modes (Query Mode or Headers Mode)
• CmcdTarget: A new configuration type, shaka.extern.CmcdTarget, was introduced. This configuration allows specifying the transmission strategy (mode=response) since targets can also be configured for event mode (mode=event), whether it's enabled (enabled), if it uses HTTP headers mode (useHeaders=true) or query parameters mode, the destination URL (url), and specific keys to include (includeKeys). For Response Mode, the mode value includes 'response'.
• Independent Handling of Transmission Modes: Request mode and Response mode can be enabled and disabled independently using the previously mentioned CmcdTarget config for response mode and the base config for request mode.
• Validation and Filtering of Keys: Allowed keys for Response Mode were added, and validation for these keys was implemented. The capability to include (includeKeys) and filter specific keys for both Request Mode and each Response Mode target was also enabled. Also, CMCD dictionary definitions were moved to a new dedicated section to improve structure
• Unit Tests: Extensive unit tests were included and unified to validate CMCD v2 functionality in both Request Mode and Response Mode.

The following keys are defined in the CMCD v2 specification but are not calculated or attached to requests/responses in the cmcd_manager.js code:

• Common & Request Mode Keys:
  • ab (Aggregate encoded bitrate)
  • tbl (Target Buffer length)
  • cdn (CDN Id)
  • bg (Backgrounded)
  • sta (State)
  • ts (Timestamp)
  • tpb (Top playable bitrate)
  • lb (Lowest encoded bitrate)
  • tab (Top aggregated encoded bitrate)
  • lab (Lowest aggregated encoded bitrate)
  • pt (Playhead time)
  • ec (Player Error Code)
• Response Mode Keys:
  • rc (Response code)
  • ttfb (Time to first byte)
  • ttfbb (Time to first body byte)
  • ttlb (Time to last byte)
  • url (Request URL)
  • cmsdd (CMSD Dynamic Header)
  • cmsds (CMSD Static Header)

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