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>

DEVELOPMENT.adoc

@@ -40,6 +40,7 @@ pkl-cli/build/executable/jpkl                   # run Java executable
 pkl-cli/build/executable/pkl-macos-amd64        # run Mac executable
 pkl-cli/build/executable/pkl-linux-amd64        # run Linux executable
 pkl-cli/build/executable/pkl-alpine-linux-amd64 # run Alpine Linux executable 
+pkl-cli/build/executable/pkl-windows-amd64.exe  # run Windows executable 
 ----
 
 == Update Gradle
@@ -68,6 +69,13 @@ based on version information from https://search.maven.org, https://plugins.grad
 * ANTLR code generation is performed by task `:pkl-core:generateGrammarSource`
 ** Output dir is `generated/antlr/`
 
+== Remote JVM Debugging
+
+To enable remote JVM debugging when running Gradle tasks (e.g. test), add the flag `-Djvmdebug=true`.
+This will listen on port 5005.
+
+Example: `./gradlew test -Djvmdebug=true`
+
 == Resources
 For automated build setup examples see our https://github.com/apple/pkl/blob/main/.circleci/[CircleCI] jobs like our https://github.com/apple/pkl/blob/main/.circleci/jobs/BuildNativeJob.pkl[BuildNativeJob.pkl], where we build Pkl automatically.