Fixes issues with tables that contain non-comparable columns

[SvdSinner]

Fixes issues with tables that contain non-comparable columns (XML, TXT, NTEXT)

[SvdSinner]

I made these changes in a style to mimic existing code. Feel welcome to tweak it, reformat it, etc. in any way you would like

[SvdSinner]

I'm not sure what to do with the failed MySql & MariaDB Tests. This PR doesn't touch any of that functionality. If I need to do something to fix these tests, please let me know.

[Mimetis]

Hey @SvdSinner

I've reviewed your PR, and I think you've found a pretty interesting solution.
Indeed, there is some failed tests, but I'll fixes them, no worry

I've reviewed the SQL generated by the GetChanges stored proc and I remember now, why we have a distinct in the query.
It's only used when we have a filter associated with the query.

If there is no filter, there is no benefits to add a distinct to the Select clause (as the tracking table has a 1-1 relationship with its parent table)

I'm currently working on refactoring tests and some providers routine, but once it's done, I will work on your PR, to fix everything.

Thanks for this great solution to improve the support of old text and ntext fields! (That's being said, please... don't use them :D )

[SvdSinner]

I realized there were some bugs in the ChangeTracking project that this caused. There is now a new commit that fixes the 3 typos that caused the bugs.

[Mimetis]

Hey @SvdSinner

Sorry to come back to you so late.
I was struggling with the refactor of all the tests and the integration of the Postgres provider.

I've made some adjustments in the GetChanges stored procedures generation for SQL Server.
Can you update your PR to resolve the conflicts and be sure your adjustments for "Xml", "Text", "NText" are generated only when filter != null ?

Once it's done, I will make the rights adjustments to integrate the corresponding's tests and be sure it's working fine with all the other providers.

Thanks a ton for your contribution!

[Mimetis]

Thanks !
I will make the relevant tests before the next release

[Mimetis]

I'm sorry @SvdSinner, I had to revert back your PR (see #936 ) as all tests are failing.