feat: Add Rust Plugins - Set/re-set cookies

[victorwoli]

This plugin lets you set, reset, or delete a domain cookie before the request reaches the Cloud/Media CDN cache. You can create session cookies or time-based cookies using Apache log format. If a cookie already exists from the origin, the plugin can overwrite it or remove the set-cookie header entirely.

[snippet-bot]

Here is the summary of changes.

You are about to add 1 region tag.

• plugins/samples/set_reset_cookie/plugin.rs:15, tag serviceextensions_plugin_set_reset_cookie

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[mpwarres]

There look to be some compilation errors, e.g.:

error: environment variable `OUT_DIR` not defined at compile time
  --> samples/set_reset_cookie/plugin.rs:21:18
   |
21 | include!(concat!(env!("OUT_DIR"), "/cookie_config.rs"));
   |                  ^^^^^^^^^^^^^^^
   |
   = help: Cargo sets build script variables at run time. Use `std::env::var("OUT_DIR")` instead
   = note: this error originates in the macro `env` (in Nightly builds, run with -Z macro-backtrace for more info)

error[E0433]: failed to resolve: use of undeclared crate or module `protobuf`
   --> samples/set_reset_cookie/plugin.rs:292:5
    |
292 |     protobuf::text_format::parse_from_str(text).map_err(|e| e.to_string())
    |     ^^^^^^^^ use of undeclared crate or module `protobuf`

error[E0412]: cannot find type `CookieConfig` in this scope
  --> samples/set_reset_cookie/plugin.rs:32:25
   |
32 |     cookie_configs: Vec<CookieConfig>,
   |                         ^^^^^^^^^^^^ not found in this scope
   |
help: you might be missing a type parameter
   |
31 | struct CookieManagerRootContext<CookieConfig> {
   |                                ++++++++++++++

error[E0412]: cannot find type `CookieManagerConfig` in this scope
  --> samples/set_reset_cookie/plugin.rs:61:21
   |
61 |         let config: CookieManagerConfig = match parse_text_proto(&config_string) {
   |                     ^^^^^^^^^^^^^^^^^^^ not found in this scope

error[E0412]: cannot find type `CookieConfig` in this scope
   --> samples/set_reset_cookie/plugin.rs:135:25
    |
135 |     cookie_configs: Vec<CookieConfig>,
    |                         ^^^^^^^^^^^^ not found in this scope
    |
help: you might be missing a type parameter