client: Add support for HTTP/HTTPS proxy (#30812)

Closes #30732

I tested it on my machine, and the HTTP proxy is working properly now.

Release Notes:

- N/A

Cargo.lock

@@ -2792,6 +2792,7 @@ dependencies = [
  "anyhow",
  "async-recursion 0.3.2",
  "async-tungstenite",
+ "base64 0.22.1",
  "chrono",
  "clock",
  "cocoa 0.26.0",
@@ -2803,6 +2804,7 @@ dependencies = [
  "gpui_tokio",
  "http_client",
  "http_client_tls",
+ "httparse",
  "log",
  "parking_lot",
  "paths",
@@ -2823,6 +2825,7 @@ dependencies = [
  "time",
  "tiny_http",
  "tokio",
+ "tokio-native-tls",
  "tokio-socks",
  "url",
  "util",