feat: add `lapack/base/dptts2`

[Pranavchiku]

Towards #2464

Description

What is the purpose of this pull request?

This pull request adds initial implementation for lapack/base/dptts2.

Related Issues

Does this pull request have any related issues?

No.

Questions

Any questions for reviewers of this pull request?

No.

Other

Any other information relevant to this pull request? This may include screenshots, references, and/or implementation notes.

No.

Checklist

TODO:

• [x] Add tests for strideB1, strideB2.
• [x] Refactor implementation ( loop interchange ) -- can't be done

Please ensure the following tasks are completed before submitting this pull request.

• [x] Read, understood, and followed the contributing guidelines.

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@stdlib-js/reviewers

[Pranavchiku]

I think this PR can now have a final review.