fix: Fix growing factor for capacity in Array

[MaxGraey]

Fix #1798

• Now internal capacity growing by factor of two.
• Initial capacity changed from 0 to 8 elements

Performance results for sequentially push 1,000,000 items into empty i32 array (--runtime=incremental)

Browser	master ms	this PR ms	JavaScript's Array (baseline), ms
Firefox 88	61557	7	10
Chrome 90	69552	8	11.4

• I've read the contributing guidelines

[dcodeIO]

Two things:

• Skip doubling when setting .length, as it doesn't typically imply a series of .pushes coming afterwards. Memory is precious.
• Account for the case where doubling would overflow maximum block size, and cap to maximum valid block size there. Otherwise growing at half maximum block size would always fail. Probably also needs a check that after all these computations, the new size is actually larger or equal to the originally requested capacity before doubling/capping, so we don't end up with a corrupted object.

[trusktr]

Wow, big speed up!