Move autcompletion for globals to __builtins__.py from internal stubs. (#675)

## Changes
We are deprecating internal type stubs in favour of python sdk. Python
sdk currently only provides typings for dbutils. This adds typings for
other globals to `__builtins__.py`.

**Removed docstrings** for these globals since they were 10+ lines each,
adding a big chunk to the user's builtins file.

* displayHTML()
* display

Author: kartikgupta-db

packages/databricks-vscode/resources/python/stubs/__builtins__.pyi

@@ -0,0 +1,16 @@
+from databricks.sdk.runtime import *
+from pyspark.sql.session import SparkSession
+from pyspark.sql.functions import udf as U
+from pyspark.sql.context import SQLContext
+
+udf = U
+spark: SparkSession
+sc = spark.sparkContext
+sqlContext: SQLContext
+sql = sqlContext.sql
+table = sqlContext.table
+getArgument = dbutils.widgets.getArgument
+
+def displayHTML(html): ...
+
+def display(input=None, *args, **kwargs): ...

packages/databricks-vscode/src/language/ConfigureAutocomplete.ts

@@ -13,9 +13,24 @@ import {WorkspaceStateManager} from "../vscode-objs/WorkspaceState";
 import {MsPythonExtensionWrapper} from "./MsPythonExtensionWrapper";
 import {DbConnectInstallPrompt} from "./DbConnectInstallPrompt";
 
-const importString = "from databricks.sdk.runtime import *";
+async function getImportString(context: ExtensionContext) {
+    try {
+        return await readFile(
+            context.asAbsolutePath(
+                path.join("resources", "stubs", "__builtins__.pyi")
+            ),
+            "utf-8"
+        );
+    } catch (e: unknown) {
+        if (e instanceof Error) {
+            window.showErrorMessage(
+                `Can't read internal type stubs for autocompletion. ${e.message}`
+            );
+        }
+    }
+}
 
-type StepResult = "Skip" | "Cancel" | "Error" | "Silent" | undefined;
+type StepResult = "Skip" | "Cancel" | "Error" | undefined;
 
 interface Step {
     fn: (dryRun: boolean) => Promise<StepResult>;
@@ -170,6 +185,11 @@ export class ConfigureAutocomplete implements Disposable {
 
         const builtinsPath = path.join(builtinsDir, "__builtins__.pyi");
 
+        const importString = await getImportString(this.context);
+        if (importString === undefined) {
+            return "Error";
+        }
+
         if (
             builtinsFileExists &&
             (await readFile(builtinsPath, "utf-8")).includes(importString)