Apply "Initial refactoring of incremental materialization"

[hiloboy0119]

Problem

dbt-spark uses the old method of applying incremental materialization macros.

This PR is a draft because I also dropped support for python 3.8 to get tests to pass. I will remove that commit when pull/1121 is merged

Solution

Applies "Initial refactoring of incremental materialization" (dbt-labs/dbt-core#5359).

Now it uses adapter.get_incremental_strategy_macro instead of dbt-spark's dbt_spark_get_incremental_sql macro to dispatch the incremental strategy macro.

Checklist

• I have read the contributing guide and understand what's expected of me
• 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
• [] 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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Thank you for your pull request and welcome to our community. We could not parse the GitHub identity of the following contributors: Drew Goya.
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