Server side batch changes: engineering milestones

Created by: mrnugget

Vision: PD 26 APPROVED: server side batch changes | draft documentation

Impacted customers

https://sourcegraph2020.lightning.force.com/lightning/r/Product_Gap__c/a1B5b00000K43ydEAB/view

See #21018 (closed) for a high-level feature description.

---

The following engineering milestones are extracted from the first draft in our scratch document.

While progressing down the list of EMs they will be converted into separate tickets. Each EM might result in follow-up tickets that move into another EM.

• EM0: Get something running
• EM1: Demo-able SSBC - Customers can see it, but not use it themselves yet
  • https://github.com/sourcegraph/sourcegraph/issues/22550
  • #22766 (closed)
  • #23496 (closed)
• EM2: Customers can use Experimental version of SSBC
  • https://github.com/sourcegraph/sourcegraph/issues/24421
  • Add a batch spec validation for SSBC that disallows files: to be used in SSBC (for now)
  • #25962 (closed)
  • #26143 (closed)
  • #26142 (closed)
  • #26796 (closed)
  • #27436
• EM3: Minimum Lovable Product aka Beta
  • #26918 (closed)
  • #29688 (closed)
  • #30524 (closed)
  • #26919 (closed)
  • #31103 (closed)
  • #31104 (closed)
  • #31105 (closed)
  • #26503 (closed)
  • #26781 (closed)
• EM4: SSBC is a mature feature that meets our quality bar
  • #31090 (closed)