[WIP] Allow duplicate prefix declarations when parsing RDF or SPARQL

[Copilot]

Thanks for assigning this issue to me. I'm starting to work on it and will keep this PR's description up to date as I form a plan and make progress.

Original issue description:

Allow for duplicate prefix declarations when both the namespace and prefix are exactly the same. We do not want to allow for duplicate prefix declarations if they are relative namespaces and where the base has changed between the first and second declarations making the effective namespace different.

We want this for:

• SPARQL queries
• SHACL shapes
• All RDF parsers

Original prompt

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This section details on the original issue you should resolve

<issue_title>Allow duplicate prefix declarations when parsing RDF or SPARQL</issue_title>
<issue_description>Allow for duplicate prefix declarations when both the namespace and prefix are exactly the same. We do not want to allow for duplicate prefix declarations if they are relative namespaces and where the base has changed between the first and second declarations making the effective namespace different.

We want this for:

• SPARQL queries
• SHACL shapes
• All RDF parsers</issue_description>

Comments on the Issue (you are @copilot in this section)

Fixes #5464

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[Copilot]

@hmottestad Unfortunately, I hit an error while trying to use the custom Copilot setup steps configured for this repository and had to close this PR. The error I am seeing is:

No `copilot-setup-steps` job found in your `copilot-setup-steps.yml` workflow file. Please ensure you have a single job named `copilot-setup-steps`. For more details, see https://gh.io/copilot/actions-setup-steps.

Once you or someone with the necessary access fixes the problem, please unassign and then reassign issue #0 to me and I'll retry. Thanks!