Add development environment detection

[marcotc]

This PR adds a utility to detect if ddtrace is running in a development environment (an environment that is unlikely to need to send traces, profiles, perform appsec checking).

This will enable us to selectively disable heavy features (background workers, network requests) performed by ddtrace when the environment does not need it. This is especially helpful when running tests with ddtrace installed.

[ivoanjo]

👍 LGTM

I suspect you're already aware (because you reused some code from it?) but just-in-case I'll point out that the EnvironmentLogger does something similar so it would be a good target to be updated to use the new helper:

dd-trace-rb/lib/datadog/core/diagnostics/environment_logger.rb

Lines 39 to 53 in b1bec43

	# Are we logging the environment data?
	def log?
	startup_logs_enabled = Datadog.configuration.diagnostics.startup_logs.enabled
	if startup_logs_enabled.nil?
	!repl? # Suppress logs if we running in a REPL
	else
	startup_logs_enabled
	end
	end
	REPL_PROGRAM_NAMES = %w[irb pry].freeze
	def repl?
	REPL_PROGRAM_NAMES.include?($PROGRAM_NAME)
	end

[ivoanjo]

This made me think that one possible alternative implementation strategy is to maybe have a proc-per-thing we want to detect, e.g.

RSPEC_PROBE = proc { $PROGRAM_NAME.end_with?(RSPEC_PROGRAM_NAME) }
MINITEST_PROBE = proc { ... }

def test?(test_probes: [RSPEC_PROBE, MINITEST_PROBE])
  test_probes.any?(&:call)
end

then we could override individual probes (or even dependency inject them).

This to say -- it came to mind; I think the current version is great as well so as usual with my random suggestions, feel free to ignore :)

[marcotc]

I agree that this suggested approach looks good!

I think the file is small now to keep it as it, but it's definitely a great alternative.

[marcotc]

The EnvironmentLogger is undergoing a big refactoring by @sarahchen6 as we speak, I didn't want to refactor it as to avoid conflicts, but I agree that they will have to converge in the future.

[codecov-commenter]

Codecov Report

Merging #3036 (cd17e14) into master (6031043) will increase coverage by 0.03%.
Report is 20 commits behind head on master.
The diff coverage is 96.05%.

@@            Coverage Diff             @@
##           master    #3036      +/-   ##
==========================================
+ Coverage   98.08%   98.12%   +0.03%     
==========================================
  Files        1317     1323       +6     
  Lines       74362    74649     +287     
  Branches     3402     3403       +1     
==========================================
+ Hits        72941    73248     +307     
+ Misses       1421     1401      -20     

Files Changed	Coverage Δ
spec/datadog/profiling/validate_benchmarks_spec.rb	100.00% <ø> (ø)
spec/datadog/core/environment/execution_spec.rb	91.89% <91.89%> (ø)
lib/datadog/core/environment/execution.rb	100.00% <100.00%> (ø)
lib/datadog/tracing/contrib.rb	100.00% <100.00%> (ø)
.../datadog/tracing/contrib/suite/integration_spec.rb	100.00% <100.00%> (ø)
spec/datadog/tracing/contrib_spec.rb	100.00% <100.00%> (ø)

... and 8 files with indirect coverage changes

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[ivoanjo]

👍 LGTM