Destroy the process during coroutine cancellation

[pgreze]

Aiming to address #5 relying on the thread I opened in the Kotlin Slack: https://kotlinlang.slack.com/archives/C1CFAFJSK/p1627981249052500

#6 was initially proposed but it was not enough, because relying on a process with an active stdout (see the EndlessInputStream).
I considered several alternatives, including:

1. a 3rd async to regularly check the isActive state, and/or
2. add support for cancellation on all stdin/stdout operations, not just the stdout one.

At the end, have both should ensure cancelled operations for most cases.

[github-actions]

Unit Test Results

  7 files  ±0    7 suites  ±0   4s ⏱️ ±0s
23 tests ±0  23 ✔️ ±0  0 💤 ±0  0 ❌ ±0 

Results for commit a565a6e. ± Comparison against base commit a565a6e.

♻️ This comment has been updated with latest results.

[codecov-commenter]

Codecov Report

Merging #7 (7915147) into main (4043ea9) will decrease coverage by 1.45%.
The diff coverage is 57.14%.

@@             Coverage Diff              @@
##               main       #7      +/-   ##
============================================
- Coverage     76.11%   74.66%   -1.46%     
  Complexity        3        3              
============================================
  Files             4        4              
  Lines            67       75       +8     
  Branches         33       37       +4     
============================================
+ Hits             51       56       +5     
- Partials         16       19       +3     

Impacted Files	Coverage Δ
...c/main/kotlin/com/github/pgreze/process/Process.kt	68.88% <57.14%> (-1.39%)	⬇️

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