4464 fix generated default column value using in PostgreSQL and Oracle for char/clob data types

[LonwoLonwo]

Impact

• Bug fix (non-breaking change which fixes expected existing functionality)
• Enhancement/New feature (adds functionality without impacting existing logic)
• Breaking change (fix or feature that would cause existing functionality to change)

TypeBug - bug fixes

Description

So, I'm trying to fix the case from #4464

The first part of this PR - is avoiding duplication of the GENERATED ALWAYS AS part.
And second - an attempt to not add quotes around the function GENERATED ALWAYS AS for character/clob columns.
I understand that this is a terrible solution - trying to guess by the string beginning - if this default value is a function or not.
But I do not see other good options.
I tried to add to the ClobType#objectToSql, but it is not general enough.
So, I am open for discussion.

Things to be aware of

I'm not sure about the test part, also.

Things to worry about

Can users use the "GENERATED ALWAYS AS" syntax just for default values? I really do not know.

[LonwoLonwo]

Oops.

[filipelautert]

Almost there :)
The assertion failed as it is not able to find our sql fragment. The generated SQL below is:

<column defaultValueComputed="GENERATED ALWAYS AS (&quot;QTY&quot;*&quot;PRICE&quot;)" name="TOTALVALUE" type="NUMBER(*, 0)"/>

So in my next commit I'm removing " from virtColumnDef variable... and seems it works. I wonder if this is the best solution @LonwoLonwo @MalloD12 , but at least it is working now :)

[MalloD12]

Approved.

Thanks @LonwoLonwo for this PR, for applying the required changes, and for your patience. Code changes look good to me. Build and all tests have been successfully executed.

It would be good if we can test running the Oracle test added in some different version than the one use for OracleIntegrationTest suite (oracle-xe:18-slim). @rberezen could you please do that when you review this PR? This test I'm talking about was failing on the mentioned version, but using the generated SQL and executing it in a newer version was successfully executed, so I would like to make sure that now it pass on version 18 it also works in newer versions.