custom recipes: move behind experimental flag

[abeatrix]

• moves custom recipes behind an experimental flag: cody.experimental.customRecipes
• add customRecipes to status bar options
• remove running git command on startup for MyToolsProvider
• fix: context JSON string escaping issue causing Request failed: found consecutive messages with the same speaker 'assistant' (slack for context)
• improve context retrieve from current directory for unit test prompt-testing through custom recipes
• add package.json as context for unit test prompt through custom recipes

Test plan

Try using the status bar to toggle custom recipes and see if it shows up in the recipes tab accordingly

JSON Output After:

JSON Output Before:

[philipp-spiess]

approve to unblock