Add support for Windows (#492)

This adds support for Windows.
The in-language path separator is still `/`, to ensure Pkl programs are cross-platform.

Log lines are written using CRLF endings on Windows.
Modules that are combined with `--module-output-separator` uses LF endings to ensure
consistent rendering across platforms.

`jpkl` does not work on Windows as a direct executable.
However, it can work with `java -jar jpkl`.

Additional details:

* Adjust git settings for Windows
* Add native executable for pkl cli
* Add jdk17 windows Gradle check in CI
* Adjust CI test reports to be staged within Gradle rather than by shell script.
* Fix: encode more characters that are not safe Windows paths
* Skip running tests involving symbolic links on Windows (these require administrator privileges to run).
* Introduce custom implementation of `IoUtils.relativize`
* Allow Gradle to initialize ExecutableJar `Property` values
* Add Gradle flag to enable remote JVM debugging

Co-authored-by: Philip K.F. Hölzenspies <holzensp@gmail.com>

.circleci/jobs/SimpleGradleJob.pkl

@@ -15,12 +15,14 @@
 //===----------------------------------------------------------------------===//
 extends "GradleJob.pkl"
 
-import "package://pkg.pkl-lang.org/pkl-pantry/com.circleci.v2@1.1.0#/Config.pkl"
+import "package://pkg.pkl-lang.org/pkl-pantry/com.circleci.v2@1.1.2#/Config.pkl"
 
 name: String = command
 
 command: String
 
+os = "linux"
+
 steps {
   new Config.RunStep {
     name = module.name