Add IMPORT INTO statement to import data by SQL using lightning physical mode

[D3Hunter]

Feature Request

Is your feature request related to a problem? Please describe:

Describe the feature you'd like:

Add INGEST INTO statement to import data by SQL using lightning physical mode

syntax

IMPORT INTO tbl_name [(col_name_or_user_var [, col_name_or_user_var] ...)]
[SET col_name=expr [, col_name=expr] ...]
FROM 'file_or_url'
[FORMAT string]
[WITH option=val [, option=val]...]

most syntax is similar to LOAD DATA statement.

allowed WITH options:

• character_set ='<string>'
• fields_terminated_by ='<string>'
• fields_enclosed_by ='<char>'
• fields_escaped_by ='<char>'
• fields_defined_null_by ='<string>'
• lines_starting_by ='<string>'
• lines_terminated_by ='<string>'
• skip_rows =<number>
• detached to run ingest in detached mode.
• disk_quota: see lightning disk-quota.
• checksum_table: see lightning checksum.
• max_write_speed: control how fast we write
• DISABLE_TIKV_IMPORT_MODE: to avoid switching TiKV into import mode.
• thread: to control import concurrency.

Describe alternatives you've considered:

Teachability, Documentation, Adoption, Migration Strategy:

[D3Hunter]

most code changes links to issue #40499

[D3Hunter]

this part is released in v7.2.0, so close it