[Rust] [DataFusion] Implement get_supertype correctly

[asfimport]

The current implementation of get_supertype (used in type coercion logic) is very hacky and should be re-implemented with better unit tests as well.

Reporter: Andy Grove / @andygrove
Assignee: Jorge Leitão / @jorgecarleitao

Related issues:

• [Rust] [DataFusion] logical schema = physical schema is not true (is duplicated by)

PRs and other links:

• GitHub Pull Request #4019
• GitHub Pull Request #7253

_{Note: This issue was originally created as ARROW-4957. Please see the migration documentation for further details.}

[asfimport]

Krisztian Szucs / @kszucs:
The pull request was closed because of inactivity, so I'm postponing it to 1.0

[asfimport]

Andy Grove / @andygrove:
I have unassigned myself from this issue since I have too many other issues I am working on and don't want to block progress on this

[asfimport]

Jorge Leitão / @jorgecarleitao:
I believe that this was fixed as part of ARROW-9809.