[Feature] make header row optional for dbt seeds

[aammett]

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 functionality, rather than a Big Idea better suited to a discussion

Describe the feature

If I've configured my seed's column names in a yml file, I don't want to also keep a header row up-to-date in my csv seed file.

seeds:
  - name: my_seed
    columns:
      - name: country_code
        data_type: varchar(2)
      - name: country_name
        data_type: varchar(32)

country_code,country_name
US,United States
CA,Canada
GB,United Kingdom

Instead, I should be able to configure my seed to not need a header row if I've configured my column names in yml already.

seeds:
  - name: my_seed
    config:
      header: false
    columns:
      - name: country_code
        data_type: varchar(2)
      - name: country_name
        data_type: varchar(32)

US,United States
CA,Canada
GB,United Kingdom

Describe alternatives you've considered

No response

Who will this benefit?

No response

Are you interested in contributing this feature?

dbt seed is using agate_helper.from_csv(), which needs to be updated to inherit the header params from agate.Table.from_csv()

Anything else?

issue referenced on dbt-labs/dbt#11334

[github-actions]

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