Add adapter.quote call around column names in alter_relation_add_remove_columns

[skadyan]

resolves #1231 docs dbt-labs/docs.getdbt.com/#

Problem

See #1231

Solution

Add the quote around the column names.

Checklist

• [X ] I have read the contributing guide and understand what's expected of me
• [X] I have run this code in development and it appears to resolve the stated issue
• [ ] This PR includes tests, or tests are not required/relevant for this PR
• [X ] This PR has no interface changes (e.g. macros, cli, logs, json artifacts, config files, adapter interface, etc) or this PR has already received feedback and approval from Product or DX

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[cla-bot[bot]]

Thanks for your pull request, and welcome to our community! We require contributors to sign our Contributor License Agreement and we don't seem to have your signature on file. Check out this article for more information on why we have a CLA.

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