Implement mapping model in support of SQL AST

Description

This is part of the read-by-position changes. Moving to a SQL AST means creating a mapping model defined in terms of the needs of that approach. See the `design/type-system-mapping.adoc` file in the project sources

Environment

None

Status

Assignee

Unassigned

Reporter

Steve Ebersole

Fix versions

None

Labels

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backPortable

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Suitable for new contributors

None

Requires Release Note

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Pull Request

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backportDecision

None

Priority

Major
Configure