Update scaffolding to use ScaffoldingTypeMapper

[ajcvickers]

This follows the changes made for #4425 which provides more information from the type mapper to scaffolding on what to scaffold for a given property. However, the implementation assumes that IsUnicode has been implemented and so this cannot be done until that issue is fixed--see #3420.

[rowanmiller]

When this is done, verify that decimal and numeric columns have scale/precision included in column type

[bricelam]

This work was also mentioned as part of #1671

[AndriySvyryd]

The type for decimal properties should always be specified, even if same as default, due to #6944

[ajcvickers]

@lajones Can you elaborate on why this is flagged as a breaking change?

[lajones]

@ajcvickers This is part of the overall type mapping work. Though I haven't mapped out the exact API on how that will work yet, I don't think we'll manage to get through all of that without changing any of the type-mapping API. I don't know that it will specifically affect the ScaffoldingTypeMapper yet - we'll see.

[ajcvickers]

@lajones So you are saying that using the ScaffoldingTypeMapper will affect the reverse engineering API such that it will be breaking for providers? Or that #7434 will do that, and this is part of the work needed for #7434?

[lajones]

@ajcvickers The latter. I'm saying #7434 may affect the APIs on ScaffoldingTypeMapper.

[ajcvickers]

@lajones Then I think it's okay to have only #7434 marked as breaking.

[ajcvickers]

Moving this out of preview2 since it doesn't need to be done.

[smitpatel]

Poaching this as it is needed for #7004

[smitpatel]

Fixed in #8626 & #8660
There are some inaccuracies in how it is used filed #8697

[smitpatel]

Commits 263c102 & 58c8f81