Consolidate `Expr` manipulation code so it is more discoverable and make it easier to use

[alamb]

Is your feature request related to a problem or challenge? Please describe what you are trying to do.

Code to handle manipulating conjunctions (AND) and disjunctions (OR) is sprinkled throughout the codebase making is harder to find as well as leading to duplication

It would also be nice to improve the ergonomics (like distinguishing between owned and unowned variants, for example). We have similar code to this in IOx https://github.com/influxdata/influxdb_iox/blob/95ed41f14063f53e37c10614a77a3d69c6c26188/datafusion_util/src/lib.rs#L41-L45 which I would like to contribute

Describe the solution you'd like

1. Consolidate manipulation into optimizer/utils for better discoverability, less duplication
2. Improve the API ergonomics

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Additional context
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