[Repair] Add an option whether to allow the partition column to be NULL

[xinyiZzz]

Proposed changes

Add an option allow_partition_column_nullable, which means whether to allow the partition column to be NULL.
When the option is enabled, the partition column must be NOT NULL when create table, otherwise an error will be reported.

Types of changes

• New feature (non-breaking change which adds functionality)

Checklist

• I have create an issue on (Fix [Proposal] Add an option whether to allow the partition column to be NULL #5012), and have described the bug/feature there in detail
• Compiling and unit tests pass locally with my changes
• If this change need a document change, I have updated the document

[morningman]

LGTM