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>

pkl-commons/src/main/kotlin/org/pkl/commons/Paths.kt

@@ -71,3 +71,13 @@ fun Path.deleteRecursively() {
     walk().use { paths -> paths.sorted(Comparator.reverseOrder()).forEach { it.deleteIfExists() } }
   }
 }
+
+private val isWindows by lazy { System.getProperty("os.name").contains("Windows") }
+
+/** Copy implementation from IoUtils.toNormalizedPathString */
+fun Path.toNormalizedPathString(): String {
+  if (isWindows) {
+    return toString().replace("\\", "/")
+  }
+  return toString()
+}

pkl-commons/src/main/kotlin/org/pkl/commons/Strings.kt

@@ -15,15 +15,24 @@
  */
 package org.pkl.commons
 
+import java.io.File
 import java.net.URI
 import java.nio.file.Path
+import java.util.regex.Pattern
 
 fun String.toPath(): Path = Path.of(this)
 
+private val uriLike = Pattern.compile("\\w+:[^\\\\].*")
+
+private val windowsPathLike = Pattern.compile("\\w:\\\\.*")
+
 /** Copy of org.pkl.core.util.IoUtils.toUri */
-fun String.toUri(): URI =
-  if (contains(":")) {
-    URI(this)
-  } else {
-    URI(null, null, this, null)
+fun String.toUri(): URI {
+  if (uriLike.matcher(this).matches()) {
+    return URI(this)
   }
+  if (windowsPathLike.matcher(this).matches()) {
+    return File(this).toURI()
+  }
+  return URI(null, null, this, null)
+}