[Rust][DataFusion] Implement Postgres String Functions

[asfimport]

This is a general task to add the Postgres String Functions to DataFusion.

https://www.postgresql.org/docs/13/functions-string.html

Reporter: Mike Seddon / @seddonm1
Assignee: Mike Seddon / @seddonm1

Subtasks:

• [Rust][DataFusion] Implement Postgres Length Functions
• Signature::OneOf
• Ascii/unicode functions
• Regex functions
• Pad/trim functions
• Left over functions/fixes
• [Rust][DataFusion] Concat Functions

PRs and other links:

• GitHub Pull Request #9243
• GitHub Pull Request #9509

_{Note: This issue was originally created as ARROW-11298. Please see the migration documentation for further details.}

[asfimport]

Andrew Lamb / @alamb:
Migrated to github: apache/datafusion#152