Near-final Main Survey MTL logic for repeat observations

[geordie666]

This PR updates the format of the initial MTL ledgers, and establishes MTL decisions for (non-LyA quasar) repeat observations, for the Main Survey. Updates include:

• All MWS targets are observed twice before dropping to the DONE priority.
  • The repeat observations occur at an interstitial, relatively low priority.
    • Except for MWS_BHB, which is repeated at a relatively high priority.
• All QSO targets are observed twice before dropping to the DONE priority.
  • The repeat observations occur at an interstitial, relatively low priority.
    • Except for z > 1.6 quasars, which receive 4 observations:
      • QSOs at z > 2.1 are repeated at high priority.
      • QSOs at 1.6 < z < 2.1 are repeated at relatively low priority.
  • The exact same logic is applied for secondary targets that have flavor QSO.
• All other primaries are observed once before dropping to the DONE priority.
• TARGET_STATE is expanded to include the full bit-names for all targets.
  • Previously, BGS, MWS and secondary targets only had "BGS", "MWS" or "SCND" for the bit-name.
• Some extra informational redshift columns in the ledgers:
  • ZS, which is intended to hold "RR" for redrock, "QN" for QuasarNET, etc.
  • ZINFO, which is intended as a catch-all for algorithmic updates.