KYIV, April 12 (Reuters) - Ukraine and Russia traded barbs on Wednesday over how much Kremlin's forces control the city of Bakhmut, for months the focal point of Moscow's bid to advance through eastern Ukraine. Ukrainian forces have hung on for months in Bakhmut, where the fiercest fighting of Moscow's full-scale February 2022 invasion has killed thousands of soldiers and been dubbed the "meat-grinder". "In Moscow, Kremlin spokesman Dmitry Peskov said approval of a law introducing electronic draft papers for the first time would help resolve a "mess" that ensued after a call-up of 300,000 conscripts last year to bolster its forces