Use ANSI colors for test results; more polish (#771)

Any thrown Pkl Errors are colored in the simple test report!

Also:
* Refactor `TextFormatter` to be more generic; rename to `TextFormattingStringBuilder`
* Adjust test report slightly (no emojis, add more spacing).
* Introduce `ColorTheme` class.
* Make stack frame descriptors colored as "faint"

Also: this changes the summary so it summarizes _all_ modules, rather than a summary per module.

---------

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

pkl-cli/src/main/kotlin/org/pkl/cli/CliTestRunner.kt

@@ -20,6 +20,7 @@ import org.pkl.commons.cli.*
 import org.pkl.core.Closeables
 import org.pkl.core.EvaluatorBuilder
 import org.pkl.core.ModuleSource.uri
+import org.pkl.core.TestResults
 import org.pkl.core.stdlib.test.report.JUnitReport
 import org.pkl.core.stdlib.test.report.SimpleReport
 import org.pkl.core.util.ErrorMessages
@@ -62,14 +63,17 @@ constructor(
       var failed = false
       var isExampleWrittenFailure = true
       val moduleNames = mutableSetOf<String>()
+      val reporter = SimpleReport(useColor)
+      val allTestResults = mutableListOf<TestResults>()
       for ((idx, moduleUri) in sources.withIndex()) {
         try {
           val results = evaluator.evaluateTest(uri(moduleUri), testOptions.overwrite)
+          allTestResults.add(results)
           if (!failed) {
             failed = results.failed()
             isExampleWrittenFailure = results.isExampleWrittenFailure.and(isExampleWrittenFailure)
           }
-          SimpleReport().report(results, consoleWriter)
+          reporter.report(results, consoleWriter)
           if (sources.size > 1 && idx != sources.size - 1) {
             consoleWriter.append('\n')
           }
@@ -102,6 +106,9 @@ constructor(
           failed = true
         }
       }
+      consoleWriter.append('\n')
+      reporter.summarize(allTestResults, consoleWriter)
+      consoleWriter.flush()
       if (failed) {
         val exitCode = if (isExampleWrittenFailure) 10 else 1
         throw CliTestException(ErrorMessages.create("testsFailed"), exitCode)