[Feature] Create relations as case-sensitive by default

[aranke]

Is this your first time submitting a feature request?

• I have read the expectations for open source contributors
• I have searched the existing issues, and I could not find an existing issue for this feature
• I am requesting a straightforward extension of existing dbt-snowflake functionality, rather than a Big Idea better suited to a discussion

Describe the feature

Follow-up issue from #1107 (comment).

Evaluate the impact of creating relation parts as case-sensitive by default:

1. Upper-case if quoting is off
2. Same-case if quoting is on

Describe alternatives you've considered

Use relation.as_case_sensitive() wherever required.

Who will this benefit?

dbt-snowflake maintainers

Are you interested in contributing this feature?

Sure

Anything else?

We should look at doing this "on the way in" instead of as it's used. We need to account for the fact that Snowflake makes it's relation identifiers uppercase if they are not quoted. This happens in a few cases. If we model this Snowflake behavior when the SnowflakeRelation is created, then we don't need to account for it later. This could impact other processes though, so we should be thorough about testing and be clear in the user docs.