add schema migration

[siyao-Siyang]

1. Enable schema migration for SQL DB

First time to table selection page, schema migration shows 'Not selected'.

If schema migration is enabled, assessment results will be checked. If any assessment issues that might fail schema migration are found, it will show the assessment results link to check the details.
If schema migration is not enabled, there are two cases. If there are missing tables on the target but users don't select 'migrate schema to target' option, it will show 'Not selected'. If there are no missing tables on target, it will show 'Not needed'.

There are three tabs after click 'Edit'：
The source tables exist on the target and have rows:

The source tables don't exist on the target and have rows:

The source tables dont have rows. These tables are not available to select for data migration. But if they dont exist on the target, schema migration is available.

2. Auto-mapping source database to target database.

Find if one of target database has the same name and collation to the selected source database, then this target database is set as dropdown component default value.

3. Integrate the assessment results with schema migration

User can click the 'Assessment results' link to check what issues might fail the schema migration

4. There are five scenarios:

4. 1. Full schema on target (Data only migration)
"Migrate schema to target" checkbox is disable.

4.2. Full schema missing on target

4.3. Partially schema missing on target

4.4. Failed migration

4.5. All source tables are empty.
If they don't exist on the target, the schema migration is still available but not available to select for data migration

5. Migration details list

Migration type: Schema only, Data only, Schema and data, Backup and restore

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• 0 of 0 changed or added relevant lines in 0 files are covered.
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• Overall coverage increased (+0.006%) to 41.576%

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Files with Coverage Reduction	New Missed Lines	%
extensions/notebook/src/dialog/configurePython/configurePathPage.ts	1	57.02%

Totals
Change from base Build 6828665189:	0.006%
Covered Lines:	30788
Relevant Lines:	69355

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