Create DeclarativeSection and override header/footer methods in TableViewController for when the section is DeclarativeSection

[BenShutt]

Create DeclarativeSection for common usage of declarative UITableView Sections

Motivation and Context

A common use case, allows programmers to define Section logic in the redraw rather than overriding UITableViewDelegate methods.

How Has This Been Tested?

Used in other company apps

Usage:

func redraw() {
    data = [
        DeclarativeSection(rows: [textRow]),
        DeclarativeSection(rows: answerRows, headerHeight: 16),
        DeclarativeSection(rows: answerRows, headerHeight: UITableView.automaticDimension, headerView: UILabel.header)
    ]
}

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• All new and existing tests passed.