This commit replaces all unnecessarily repeated code for decoding and
embedding blurhash canvases with separate component - <Blurhash>.
Under the hood Blurhash component will use effect dependent on its
props. This gives a few benefits: it will only be re-rendered whenever
the hash or width/height/dummy props update, and will not render if
canvas won't get to the final DOM, because then effect won't fire,
which prevents weird bugs like #14257.
Sasha Sorokin