[SQL][Docs] Update the output of printSchema and fix a typo in SQL programming guide.

We have changed the output format of `printSchema`. This PR will update our SQL programming guide to show the updated format. Also, it fixes a typo (the value type of `StructType` in Java API).

Author: Yin Huai <huai@cse.ohio-state.edu>

Closes #2630 from yhuai/sqlDoc and squashes the following commits:

267d63e [Yin Huai] Update the output of printSchema and fix a typo.

(cherry picked from commit 82a6a083a485140858bcd93d73adec59bb5cca64)
Signed-off-by: Michael Armbrust <michael@databricks.com>
[SPARK-3755][Core] avoid trying privileged port when request a non-privileged port

pwendell, ```tryPort``` is not compatible with old code in last PR, this is to fix it.
And after discuss with srowen renamed the title to "avoid trying privileged port when request a non-privileged port". Plz refer to the discuss for detail.

Author: scwf <wangfei1@huawei.com>

Closes #2623 from scwf/1-1024 and squashes the following commits:

10a4437 [scwf] add comment
de3fd17 [scwf] do not try privileged port when request a non-privileged port
42cb0fa [scwf] make tryPort compatible with old code
cb8cc76 [scwf] do not use port 1 - 1024

(cherry picked from commit 8081ce8bd111923db143abc55bb6ef9793eece35)
Signed-off-by: Andrew Or <andrewor14@gmail.com>

Conflicts:
	core/src/main/scala/org/apache/spark/util/Utils.scala
[DEPLOY] SPARK-3759: Return the exit code of the driver process

SparkSubmitDriverBootstrapper.scala now returns the exit code of the driver process, instead of always returning 0.

Author: Eric Eijkelenboom <ee@userreport.com>

Closes #2628 from ericeijkelenboom/master and squashes the following commits:

cc4a571 [Eric Eijkelenboom] Return the exit code of the driver process

(cherry picked from commit 42d5077fd3f2c37d1cd23f4c81aa89286a74cb40)
Signed-off-by: Andrew Or <andrewor14@gmail.com>
SPARK-2058: Overriding SPARK_HOME/conf with SPARK_CONF_DIR

Update of PR #997.

With this PR, setting SPARK_CONF_DIR overrides SPARK_HOME/conf (not only spark-defaults.conf and spark-env).

Author: EugenCepoi <cepoi.eugen@gmail.com>

Closes #2481 from EugenCepoi/SPARK-2058 and squashes the following commits:

0bb32c2 [EugenCepoi] use orElse orNull and fixing trailing percent in compute-classpath.cmd
77f35d7 [EugenCepoi] SPARK-2058: Overriding SPARK_HOME/conf with SPARK_CONF_DIR

(cherry picked from commit f0811f928e5b608e1a2cba3b6828ba0ed03b701d)
Signed-off-by: Andrew Or <andrewor14@gmail.com>
[SPARK-3696]Do not override the user-difined conf_dir

https://issues.apache.org/jira/browse/SPARK-3696

We see if SPARK_CONF_DIR is already defined before assignment.

Author: WangTaoTheTonic <barneystinson@aliyun.com>

Closes #2541 from WangTaoTheTonic/confdir and squashes the following commits:

c3f31e0 [WangTaoTheTonic] Do not override the user-difined conf_dir

(cherry picked from commit 9d320e222c221e5bb827cddf01a83e64a16d74ff)
Signed-off-by: Andrew Or <andrewor14@gmail.com>

Conflicts:
	sbin/spark-config.sh
[SPARK-3535][Mesos] Fix resource handling.

Author: Brenden Matthews <brenden@diddyinc.com>

Closes #2401 from brndnmtthws/master and squashes the following commits:

4abaa5d [Brenden Matthews] [SPARK-3535][Mesos] Fix resource handling.

(cherry picked from commit a8c52d5343e19731909e73db5de151a324d31cd5)
Signed-off-by: Andrew Or <andrewor14@gmail.com>
[SPARK-3775] Not suitable error message in spark-shell.cmd

Modified some sentence of error message in bin\*.cmd.

Author: Masayoshi TSUZUKI <tsudukim@oss.nttdata.co.jp>

Closes #2640 from tsudukim/feature/SPARK-3775 and squashes the following commits:

3458afb [Masayoshi TSUZUKI] [SPARK-3775] Not suitable error message in spark-shell.cmd

(cherry picked from commit 358d7ffd01b4a3fbae313890522cf662c71af6e5)
Signed-off-by: Andrew Or <andrewor14@gmail.com>
[SPARK-3774] typo comment in bin/utils.sh

Modified the comment of bin/utils.sh.

Author: Masayoshi TSUZUKI <tsudukim@oss.nttdata.co.jp>

Closes #2639 from tsudukim/feature/SPARK-3774 and squashes the following commits:

707b779 [Masayoshi TSUZUKI] [SPARK-3774] typo comment in bin/utils.sh

(cherry picked from commit e5566e05b1ac99aa6caf1701e47ebcdb68a002c6)
Signed-off-by: Andrew Or <andrewor14@gmail.com>