Move Perplexity extension to dedicated repository (#34070)

Move Perplexity extension to:
https://github.com/zed-extensions/perplexity

Release Notes:

- N/A

Cargo.lock

@@ -11350,14 +11350,6 @@ version = "2.3.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "e3148f5046208a5d56bcfc03053e3ca6334e51da8dfb19b6cdc8b306fae3283e"
 
-[[package]]
-name = "perplexity"
-version = "0.1.0"
-dependencies = [
- "serde",
- "zed_extension_api 0.6.0",
-]
-
 [[package]]
 name = "pest"
 version = "2.8.0"