[BOUNTY $50] Support for asynchronously running a kernel

[CC007]

Implement a way to asynchronously run a kernel with also an easy way to wait for the kernel to end like:

Kernel k = ...;
Execution ex = k.executeAsync(...);
ex.waitUntilFinished();

[freemo]

@CC007 There is an easy path for this (run each kernel in its own cpu thread) but i dont like that. It should be possible to do from a single thread in theory. I like this feature and want to try to add a bounty to try to get this one implemented. With a bounty in place would you have any interest in taking this up? If not I have a group that usually takes on most bounties, wanted to give you first dibs.

[KingParmenides]

Opened PR #192 for this bounty: #192

It adds Execution ex = kernel.executeAsync(...) plus ex.waitUntilFinished() and focused tests for completion, multi-pass execution, and failure propagation.

Bounty payout addresses if needed:

• BTC: 39Q34P8A7g375yqEr8buvNJkUbRgKfbKQZ
• USDC: 0x9343305D20d12c0aDF97F943bb2152F8eC4Cef4C

[gshaowei6]

Opened PR #213 for this bounty: #213

Validation:

• RED: KernelAsyncExecutionTest initially failed to compile because com.aparapi.Execution and Kernel.executeAsync(Range) did not exist.
• Focused compile with javac -g --release 8 for Execution, Kernel, and KernelAsyncExecutionTest.
• JUnitCore com.aparapi.runtime.KernelAsyncExecutionTest com.aparapi.runtime.MultiplePassesMemoryConsumptionTest passed (2 tests).
• git diff --check passed.