Add colours to Pkl errors in Cli output

To make error messages from Pkl eval easier to read, this change uses
the Jansi library to colour the output, making it quicker and easier to
scan error messages and understand what's happened.

The Jansi library also detects if the CLI output is a terminal capable
of handling colours, and will automatically strip out escape codes if
the output won't support them (e.g. piping the output somewhere else).

pkl-core/src/test/kotlin/org/pkl/core/EvaluateTestsTest.kt

@@ -3,7 +3,6 @@ package org.pkl.core
 import org.pkl.commons.createTempFile
 import org.assertj.core.api.Assertions.assertThat
 import org.junit.jupiter.api.Assertions.assertFalse
-import org.junit.jupiter.api.Assertions.assertTrue
 import org.junit.jupiter.api.Test
 import org.junit.jupiter.api.io.TempDir
 import org.pkl.commons.writeString
@@ -11,7 +10,6 @@ import org.pkl.core.ModuleSource.*
 import java.nio.file.Files
 import java.nio.file.Path
 import kotlin.io.path.createFile
-import kotlin.io.path.name
 
 class EvaluateTestsTest {
 

pkl-core/src/test/kotlin/org/pkl/core/EvaluatorTest.kt

@@ -429,7 +429,7 @@ class EvaluatorTest {
     val evaluatorBuilder = EvaluatorBuilder.preconfigured().setModuleCacheDir(cacheDir)
     val project = Project.load(modulePath("/org/pkl/core/project/project6/PklProject"))
     evaluatorBuilder.setProjectDependencies(project.dependencies).build().use { evaluator ->
-      assertThatCode { 
+      assertThatCode {
         evaluator.evaluateOutputText(modulePath("/org/pkl/core/project/project6/globWithinDependency.pkl"))
       }.hasMessageContaining("""
         Cannot resolve import in local dependency because scheme `modulepath` is not globbable.

pkl-core/src/test/kotlin/org/pkl/core/project/ProjectTest.kt

@@ -149,8 +149,9 @@ class ProjectTest {
         .setModuleCacheDir(null)
         .setHttpClient(httpClient)
         .build()
-      assertThatCode { evaluator.evaluate(ModuleSource.path(projectDir.resolve("bug.pkl"))) }
-        .hasMessageStartingWith("""
+      assertThatCode {
+        evaluator.evaluate(ModuleSource.path(projectDir.resolve("bug.pkl")))
+      }.hasMessageStartingWith("""
         –– Pkl Error ––
         Cannot download package `package://localhost:0/fruit@1.0.5` because the computed checksum for package metadata does not match the expected checksum.