Remove inlineMarkdown representation

...to speed up parsing speed and GC load.

Standalone renderer works, but no markdown tests.

markdown/core/src/main/kotlin/org/jetbrains/jewel/markdown/MarkdownBlock.kt

@@ -1,6 +1,6 @@
 package org.jetbrains.jewel.markdown
 
-import org.intellij.lang.annotations.Language
+import org.commonmark.node.Node
 
 public sealed interface MarkdownBlock {
 
@@ -80,4 +80,4 @@ public interface BlockWithInlineMarkdown {
  * [block-level elements][MarkdownBlock].
  */
 @JvmInline
-public value class InlineMarkdown(@Language("Markdown") public val content: String)
+public value class InlineMarkdown(public val content: Node)

markdown/core/src/main/kotlin/org/jetbrains/jewel/markdown/processing/MarkdownProcessor.kt

@@ -189,8 +189,7 @@ public class MarkdownProcessor(private val extensions: List<MarkdownProcessorExt
         return MarkdownBlock.HtmlBlock(content = literal.trimEnd('\n'))
     }
 
-    private fun Node.contentsAsInlineMarkdown() =
-        InlineMarkdown(buildString { appendInlineMarkdownFrom(this@contentsAsInlineMarkdown) })
+    private fun Node.contentsAsInlineMarkdown() = InlineMarkdown(this)
 
     private fun StringBuilder.appendInlineMarkdownFrom(
         node: Node,
@@ -341,7 +340,7 @@ public class MarkdownProcessor(private val extensions: List<MarkdownProcessorExt
         return "$backticks$this$backticks"
     }
 
-    private fun InlineMarkdown.isBlank(): Boolean = content.isBlank()
+    private fun InlineMarkdown.isBlank(): Boolean = content.firstChild == null
 
     private fun plainTextContents(node: Node): String = textContentRenderer.render(node)
 }

markdown/core/src/main/kotlin/org/jetbrains/jewel/markdown/rendering/DefaultInlineMarkdownRenderer.kt

@@ -30,9 +30,6 @@ public open class DefaultInlineMarkdownRenderer(rendererExtensions: List<Markdow
 
     public constructor(vararg extensions: MarkdownProcessorExtension) : this(extensions.toList())
 
-    private val commonMarkParser =
-        Parser.builder().extensions(rendererExtensions.map { it.parserExtension }).build()
-
     private val plainTextRenderer =
         TextContentRenderer.builder()
             .extensions(rendererExtensions.map { it.textRendererExtension })
@@ -43,7 +40,7 @@ public open class DefaultInlineMarkdownRenderer(rendererExtensions: List<Markdow
         styling: InlinesStyling,
     ): AnnotatedString =
         buildAnnotatedString {
-            val node = commonMarkParser.parse(inlineMarkdown.content)
+            val node = inlineMarkdown.content
             appendInlineMarkdownFrom(node, styling)
         }