[crashtracker] Make C example emit a file

[danielsn]

What does this PR do?

What it says on the tin

Motivation

The current C example was hard to follow, since you needed an instrumented agent to see where the output went. This is cleaner.

Additional Notes

Anything else we should know when reviewing?

How to test the change?

Describe here in detail how the change can be validated.

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 70.49%. Comparing base (1f350c9) to head (bc72132).

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #539   +/-   ##
=======================================
  Coverage   70.49%   70.49%           
=======================================
  Files         208      208           
  Lines       28397    28397           
=======================================
  Hits        20019    20019           
  Misses       8378     8378           

Components	Coverage Δ
crashtracker	25.46% <ø> (ø)
datadog-alloc	98.73% <ø> (ø)
data-pipeline	50.00% <ø> (ø)
data-pipeline-ffi	0.00% <ø> (ø)
ddcommon	86.43% <ø> (ø)
ddcommon-ffi	75.29% <ø> (ø)
ddtelemetry	58.95% <ø> (ø)
ipc	84.13% <ø> (ø)
profiling	78.09% <ø> (ø)
profiling-ffi	56.76% <ø> (ø)
serverless	0.00% <ø> (ø)
sidecar	35.42% <ø> (ø)
sidecar-ffi	0.00% <ø> (ø)
spawn-worker	54.98% <ø> (ø)
trace-mini-agent	71.14% <ø> (ø)
trace-normalization	98.24% <ø> (ø)
trace-obfuscation	95.73% <ø> (ø)
trace-protobuf	77.16% <ø> (ø)
trace-utils	91.63% <ø> (ø)

[pr-commenter]

Benchmarks

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[morrisonlevi]

Looks good on my side.