PY-46321 Added Markdown code fence aliases for PyDocstring and Python

* PyDocstring: "pycon", "python-repl"
* Python: "py", "python3"

I've added the links to the documents describing popular references to `PyCodeFenceLanguageProvider`.

GitOrigin-RevId: 6cafb15c9655434f5d69aa47eb7472b634364377

python/python-markdown/intellij.python.markdown.iml

@@ -0,0 +1,16 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<module type="JAVA_MODULE" version="4">
+  <component name="NewModuleRootManager" inherit-compiler-output="true">
+    <exclude-output />
+    <content url="file://$MODULE_DIR$">
+      <sourceFolder url="file://$MODULE_DIR$/resources" type="java-resource" />
+      <sourceFolder url="file://$MODULE_DIR$/src" isTestSource="false" />
+    </content>
+    <orderEntry type="inheritedJdk" />
+    <orderEntry type="sourceFolder" forTests="false" />
+    <orderEntry type="library" name="kotlin-stdlib-jdk8" level="project" />
+    <orderEntry type="module" module-name="intellij.markdown" />
+    <orderEntry type="module" module-name="intellij.python.psi.impl" />
+    <orderEntry type="module" module-name="intellij.python.psi" />
+  </component>
+</module>

python/python-markdown/resources/META-INF/python-markdown-plugin.xml

@@ -0,0 +1,5 @@
+<idea-plugin>
+  <extensions defaultExtensionNs="org.intellij.markdown">
+    <fenceLanguageProvider implementation="com.jetbrains.python.markdown.PyCodeFenceLanguageProvider"/>
+  </extensions>
+</idea-plugin>

python/python-markdown/src/com/jetbrains/python/markdown/PyCodeFenceLanguageProvider.kt

@@ -0,0 +1,27 @@
+package com.jetbrains.python.markdown
+
+import com.intellij.codeInsight.completion.CompletionParameters
+import com.intellij.codeInsight.lookup.LookupElement
+import com.intellij.lang.Language
+import com.jetbrains.python.PythonLanguage
+import com.jetbrains.python.documentation.doctest.PyDocstringLanguageDialect
+import org.intellij.plugins.markdown.injection.CodeFenceLanguageProvider
+
+/**
+ * Defines major Python dialects to use in Markdown code fence blocks.
+ *
+ * These dialects are listed as classes in [highlight.js][1] and in [Linguist][2] used by GitHub.
+ *
+ * [1]: https://github.com/highlightjs/highlight.js/blob/main/SUPPORTED_LANGUAGES.md
+ * [2]: https://github.com/github/linguist/blob/master/lib/linguist/languages.yml
+ */
+class PyCodeFenceLanguageProvider : CodeFenceLanguageProvider {
+  override fun getLanguageByInfoString(infoString: String): Language? =
+    when (infoString.toLowerCase()) {
+      "pycon", "python-repl" -> PyDocstringLanguageDialect.getInstance()
+      "py", "python3" -> PythonLanguage.INSTANCE
+      else -> null
+    }
+
+  override fun getCompletionVariantsForInfoString(parameters: CompletionParameters): List<LookupElement> = emptyList()
+}