This adds a new feature to build a dependency graph of Pkl programs, following the SPICE outlined in https://github.com/apple/pkl-evolution/pull/2.
It adds:
* CLI command `pkl analyze imports`
* Java API `org.pkl.core.Analyzer`
* Pkl stdlib module `pkl:analyze`
* pkl-gradle extension `analyze`
In addition, it also changes the Gradle plugin such that `transitiveModules` is by default computed from the import graph.
Rationale: "proxy" can mean very different things (e.g. java.lang.reflect.Proxy in Java).
This makes the flag name more specific.
CLI:
* `--proxy` -> `--http-proxy`
* `--no-proxy` -> `--http-no-proxy`
Gradle:
* `proxyAddress` -> `httpProxy`
* `noProxy` -> `httpNoProxy`
* Add `--proxy` and `--no-proxy` CLI flags
* Add property `http` to `pkl:settings`
* Move `EvaluatorSettings` from `pkl:Project` to its own module and add property `http`
* Add support for proxying in server mode, and through Gradle
* Add `setProxy()` to `HttpClient`
* Add documentation
