[MINOR][MAINTENANCE] Sort the entries in .gitignore.

## What changes were proposed in this pull request?

The contents of `.gitignore` have been sorted to make it more readable. The actual contents of the file have not been changed.

## How was this patch tested?

Does not require any tests.

Author: Arun Allamsetty <arun@instructure.com>

Closes #12742 from aa8y/gitignore.

.gitignore

-*~
-*.#*
 *#*#
-*.swp
-*.ipr
+*.#*
 *.iml
+*.ipr
 *.iws
 *.pyc
 *.pyo
+*.swp
+*~
+.DS_Store
+.cache
+.classpath
+.ensime
+.ensime_cache/
+.ensime_lucene
+.generated-mima*
 .idea/
 .idea_modules/
-build/*.jar
+.project
+.scala_dependencies
 .settings
-.cache
-cache
-.generated-mima*
-work/
-out/
-.DS_Store
+/lib/
+R-unit-tests.log
+R/unit-tests.out
+build/*.jar
 build/apache-maven*
-build/zinc*
 build/scala*
-scalastyle-on-compile.generated.xml
-conf/java-opts
-conf/*.sh
+build/zinc*
+cache
+checkpoint
 conf/*.cmd
-conf/*.properties
 conf/*.conf
+conf/*.properties
+conf/*.sh
 conf/*.xml
+conf/java-opts
 conf/slaves
+dependency-reduced-pom.xml
+derby.log
+dev/create-release/*final
+dev/create-release/*txt
+dist/
 docs/_site
 docs/api
-target/
-reports/
-.project
-.classpath
-.scala_dependencies
 lib_managed/
-src_managed/
+lint-r-report.log
+log/
+logs/
+out/
 project/boot/
-project/plugins/project/build.properties
 project/build/target/
-project/plugins/target/
 project/plugins/lib_managed/
+project/plugins/project/build.properties
 project/plugins/src_managed/
-logs/
-log/
+project/plugins/target/
+python/lib/pyspark.zip
+reports/
+scalastyle-on-compile.generated.xml
+scalastyle-output.xml
+scalastyle.txt
+spark-*-bin-*.tgz
 spark-tests.log
+src_managed/
 streaming-tests.log
-dependency-reduced-pom.xml
-.ensime
-.ensime_cache/
-.ensime_lucene
-checkpoint
-derby.log
-dist/
-dev/create-release/*txt
-dev/create-release/*final
-spark-*-bin-*.tgz
+target/
 unit-tests.log
-/lib/
-scalastyle.txt
-scalastyle-output.xml
-R-unit-tests.log
-R/unit-tests.out
-python/lib/pyspark.zip
-lint-r-report.log
+work/
 
 # For Hive
-metastore_db/
-metastore/
-warehouse/
 TempStatsStore/
+metastore/
+metastore_db/
 sql/hive-thriftserver/test_warehouses
+warehouse/
 
 # For R session data
-.RHistory
 .RData
+.RHistory