Feature-tracking: Add a script to merge features across repos

[dominiccooney]

Test plan

Manually tested. Patch the features files from #3846 and sourcegraph/jetbrains#1400 , then:

$ pnpm features merge ../features.json5 ~/projects/jetbrains/features5.json

Output:

{
  "editors": [
    "vscode",
    "jetbrains"
  ],
  "features": [
    {
      "name": "NotebookBasedChatUI",
      "description": "new chat UI that resembles a notebook instead of a chat session",
      "productLine": "all",
      "documentation": [],
      "editors": {
        "vscode": {
          "status": "stable"
        },
        "jetbrains": {
          "status": "planned"
        }
      },
      "tags": [
        "chat"
      ]
    },
   ...

[kalanchan]

looks good, I tried the script and it works well.

My only comment is around overwriting behaviour, maybe this can just be a process thing but we should set guidelines on when an overlay should add fields that overwrite the base file.

maybe it's as simple as "if you're touching an overlay, don't add any optional fields if not necessary"

[kalanchan]

imagine the scenario where the descriptions are different:

VS Code:

{ ... 
"name": "FireworksOnSubmission",
"description": "Animate fireworks when user submits a chat"
... }

JetBrains Overlay:

{ ... 
"name": "FireworksOnSubmission",
"description": "shoot cool fireworks when a user submits a chat"
... }

the JetBrains overlay will overwrite with the new description right? I guess it won't be that big of a problem, but we should set some guidelines to be consistent across features.json files

[kalanchan]

nice, when we automate this we can easily run something like

pnpm features merge <machine_root>/cody/featuresA.json5 <machine_root>/jetbrains/featuresB.json5