[SPARK-32839][WINDOWS] Make Spark scripts working with the spaces in paths on Windows

### What changes were proposed in this pull request?

If you install Spark under the path that has whitespaces, it does not work on Windows, for example as below:

```
>>> SparkSession.builder.getOrCreate()
Presence of build for multiple Scala versions detected (C:\...\assembly\target\scala-2.13 and C:\...\assembly\target\scala-2.12).
Remove one of them or, set SPARK_SCALA_VERSION=2.13 in spark-env.cmd.
Visit https://spark.apache.org/docs/latest/configuration.html#environment-variables for more details about setting environment variables in spark-env.cmd.
Either clean one of them or, set SPARK_SCALA_VERSION in spark-env.cmd.
```

This PR fixes the whitespace handling to support any paths on Windows.

### Why are the changes needed?

To support Spark working with whitespaces in paths on Windows.

### Does this PR introduce _any_ user-facing change?

Yes, users will be able to install and run Spark under the paths with whitespaces.

### How was this patch tested?

Manually tested.

Closes apache#29706 from HyukjinKwon/window-space-path.

Authored-by: HyukjinKwon <[email protected]>
Signed-off-by: HyukjinKwon <[email protected]>

Author: HyukjinKwon

bin/find-spark-home.cmd

@@ -55,6 +55,6 @@ if "x%SPARK_HOME%"=="x" (
     set SPARK_HOME=%~dp0..
   ) else (
     rem We are pip installed, use the Python script to resolve a reasonable SPARK_HOME
-    for /f "delims=" %%i in ('%PYTHON_RUNNER% %FIND_SPARK_HOME_PYTHON_SCRIPT%') do set SPARK_HOME=%%i
+    for /f "delims=" %%i in ('%PYTHON_RUNNER% "%FIND_SPARK_HOME_PYTHON_SCRIPT%"') do set SPARK_HOME=%%i
   )
 )

bin/load-spark-env.cmd

@@ -24,7 +24,7 @@ rem conf\ subdirectory.
 if not defined SPARK_ENV_LOADED (
   set SPARK_ENV_LOADED=1
 
-  if [%SPARK_CONF_DIR%] == [] (
+  if not defined SPARK_CONF_DIR (
     set SPARK_CONF_DIR=%~dp0..\conf
   )
 
@@ -36,8 +36,8 @@ rem Setting SPARK_SCALA_VERSION if not already set.
 set SCALA_VERSION_1=2.13
 set SCALA_VERSION_2=2.12
 
-set ASSEMBLY_DIR1=%SPARK_HOME%\assembly\target\scala-%SCALA_VERSION_1%
-set ASSEMBLY_DIR2=%SPARK_HOME%\assembly\target\scala-%SCALA_VERSION_2%
+set ASSEMBLY_DIR1="%SPARK_HOME%\assembly\target\scala-%SCALA_VERSION_1%"
+set ASSEMBLY_DIR2="%SPARK_HOME%\assembly\target\scala-%SCALA_VERSION_2%"
 set ENV_VARIABLE_DOC=https://spark.apache.org/docs/latest/configuration.html#environment-variables
 
 if not defined SPARK_SCALA_VERSION (

bin/spark-class2.cmd

@@ -30,12 +30,12 @@ if "x%1"=="x" (
 
 rem Find Spark jars.
 if exist "%SPARK_HOME%\jars" (
-  set SPARK_JARS_DIR="%SPARK_HOME%\jars"
+  set SPARK_JARS_DIR=%SPARK_HOME%\jars
 ) else (
-  set SPARK_JARS_DIR="%SPARK_HOME%\assembly\target\scala-%SPARK_SCALA_VERSION%\jars"
+  set SPARK_JARS_DIR=%SPARK_HOME%\assembly\target\scala-%SPARK_SCALA_VERSION%\jars
 )
 
-if not exist "%SPARK_JARS_DIR%"\ (
+if not exist "%SPARK_JARS_DIR%" (
   echo Failed to find Spark jars directory.
   echo You need to build Spark before running this program.
   exit /b 1