🐛 utils: polyfill growBuffer

[pietrovismara]

Adds isGrowResizeSupported to test for buffer grow support and growBufferPolyfill.

[pietrovismara]

I think I've adressed your review with the last commits.

• growBuffer and its polyfill are now a single function
• I added a flag param to growBuffer to force the grow-replace strategy
• Tested growBuffer
• Added the onGrow callback and tested it

[krispya]

I'll review this, probably tomorrow morning.