[SPARK-14086][SQL] Add DDL commands to ANTLR4 Parser [WIP]

[hvanhovell]

What changes were proposed in this pull request?

This PR is built on top of #11557. It adds the DDL commands to the SQL/Core parser.

I'll add some more documentation later on.

How was this patch tested?

Existing Unit tests.

[SparkQA]

Test build #53843 has finished for PR 11905 at commit 6c5f405.

• This patch passes all tests.
• This patch merges cleanly.
• This patch adds no public classes.

[SparkQA]

Test build #53967 has finished for PR 11905 at commit d55b26f.

• This patch fails MiMa tests.
• This patch merges cleanly.
• This patch adds no public classes.

[SparkQA]

Test build #2672 has finished for PR 11905 at commit d55b26f.

• This patch fails Python style tests.
• This patch merges cleanly.
• This patch adds no public classes.

[SparkQA]

Test build #2673 has finished for PR 11905 at commit d55b26f.

• This patch fails Spark unit tests.
• This patch merges cleanly.
• This patch adds no public classes.

[hvanhovell]

retest this please

[SparkQA]

Test build #54018 has finished for PR 11905 at commit d55b26f.

• This patch passes all tests.
• This patch merges cleanly.
• This patch adds no public classes.

[SparkQA]

Test build #54290 has finished for PR 11905 at commit 808ebf8.

• This patch fails to build.
• This patch merges cleanly.
• This patch adds no public classes.

[SparkQA]

Test build #54291 has finished for PR 11905 at commit 8be1716.

• This patch fails Spark unit tests.
• This patch merges cleanly.
• This patch adds no public classes.

[SparkQA]

Test build #54306 has finished for PR 11905 at commit d5cba5c.

• This patch passes all tests.
• This patch merges cleanly.
• This patch adds no public classes.

[SparkQA]

Test build #54308 has finished for PR 11905 at commit 0d15065.

• This patch passes all tests.
• This patch merges cleanly.
• This patch adds no public classes.

[SparkQA]

Test build #54311 has finished for PR 11905 at commit 3fe7e5f.

• This patch passes all tests.
• This patch merges cleanly.
• This patch adds the following public classes (experimental):
  • implicit class EnhancedLogicalPlan(val plan: LogicalPlan) extends AnyVal

[SparkQA]

Test build #54312 has finished for PR 11905 at commit 6b336f9.

• This patch passes all tests.
• This patch merges cleanly.
• This patch adds no public classes.