(fix)(TF backend): optimized the backend implementation of ivy.linear for TF backend to make use of tf.matmul for the 2D input case

[YushaArif99]

Rewrote the implementation to use the classic (x*w.T + b) formula instead of the more sophisticated tf.einsum op which was also causing a huge slowdown during training.

PR Description

Related Issue

Closes #

Checklist

• Did you add a function?
• Did you add the tests?
• Did you run your tests and are your tests passing?
• Did pre-commit not fail on any check?
• Did you follow the steps we provided?

Socials

[github-actions]

PR Compliance Checks

Thank you for your Pull Request! We have run several checks on this pull request in order to make sure it's suitable for merging into this project. The results are listed in the following section.

Issue Reference

In order to be considered for merging, the pull request description must refer to a specific issue number. This is described in our contributing guide and our PR template.
This check is looking for a phrase similar to: "Fixes #XYZ" or "Resolves #XYZ" where XYZ is the issue number that this PR is meant to address.

Conventional Commit PR Title

In order to be considered for merging, the pull request title must match the specification in conventional commits. You can edit the title in order for this check to pass.
Most often, our PR titles are something like one of these:

• docs: correct typo in README
• feat: implement dark mode"
• fix: correct remove button behavior

Linting Errors

• Found type "null", must be one of "feat","fix","docs","style","refactor","perf","test","build","ci","chore","revert"