Refactor validation in the Knowledge submission form

[aevo98765]

Validation code is repeated multiple times within the src/components/knowledge/index.tsx file.

Validation on the question and answer pair input needs to be implemented. e.g. minimum 5 pairs and no more than 2300 words in each pair. https://github.com/instructlab/taxonomy?tab=readme-ov-file#getting-started-with-knowledge-contributions.

[aevo98765]

Consider the changes here and ensure up to date validation -> #93