Athena / Presto support for some aspects of dbt utils

[SOVALINUX]

This is a:

• bug fix PR with no breaking changes

Description & motivation

Currently I'm using dbt-unit-testing package to run unit tests and this package uses dbt-utils
My connector is Athena (Presto-based) and Athena/Presto doesn't support ilike operator - it has to be changed to more explicit regexp
Another issue is in not_null_proportion generic test due to type numeric what is not supported in Athena / Presto

Checklist

• I have verified that these changes work locally on the following warehouses (Note: it's okay if you do not have access to all warehouses, this helps us understand what has been covered)
  • BigQuery
  • Postgres
  • Redshift
  • Snowflake
  • Athena
• I followed guidelines to ensure that my changes will work on "non-core" adapters by:
  • dispatching any new macro(s) so non-core adapters can also use them (e.g. the star() source)
• I have updated the README.md (if applicable)
• I have added tests & descriptions to my models (and macros if applicable)
• I have added an entry to CHANGELOG.md

[owenprough-sift]

Some of these changes have existing implementations over in the athena-utils package.

[joellabes]

@SOVALINUX thanks for this! right now, this package is just for the core databases that dbt Labs supports; https://github.com/lalalilo/athena-utils is the place to go as @owenprough-sift says.

You might also like the discussion at #590