feat(yarn-install): install corepack, to allow dynamic installation

[secustor]

Allows to install Yarn v4 via packageManager field in package.json

Context backstage/backstage#28881

[fearphage]

This could be simplified a bit.

Suggested change

	run: |
	if [[ "${{ inputs.yarn-install-force }}" == "true" ]]; then
	npm install --force -g corepack@${{ inputs.corepack-version }}
	else
	npm install -g corepack@${{ inputs.corepack-version }}
	fi
	env:
	YARN_INSTALL_FORCE: ${{ inputs.yarn-install-force == 'true' && '--force' || '' }}
	run: |
	npm install $YARN_INSTALL_FORCE -g corepack@${{ inputs.corepack-version }}