[TB] Add pre-commit hook to enforce prettier, linting

## Problem/Concern

Stemming from https://github.com/finos/a11y-theme-builder/pull/948#issuecomment-2200477209, it was suggested that we should have a pre-commit hook in Theme Builder to enforce Prettier formatting and linting so that we know that code being sent for code review won't have to spend much time on formatting issues.

## Proposed Solution

Create a pre-commit hook so that committed code will have the correct formatting and linting.

No file or test is named. Start by locating the repository's existing formatting and linting commands and the Git hook configuration; done means commits run both checks and reject code that fails them.

Written by the indexing model from the issue text.