Break 070_subprograms into chapters #2042

Job	Run time
List-Courses	4s
Labs-Slides	1m 5s
Labs (ubuntu-latest)	41s
Contrib scripts check	1m 15s
Python scripts black lint check	7s
Slides (static_analysis_via_compiler)	1m 13s
Slides (fundamentals_of_ada)	9m 40s
Slides (gnat_project_facility)	2m 21s
Slides (gnat_studio)	1m 21s
Slides (toolchain)	1m 56s
Slides (gnatsas)	2m 24s
Slides (gnatdas)	2m 5s
Slides (spark_for_ada_programmers)	3m 46s
Slides (advanced_exception_analysis)	1m 6s
Slides (fundamentals_of_ada/opat.txt)	2m 51s
Slides (fundamentals_of_ada/standard_course.txt)	2m 52s
Slides (fundamentals_of_ada/advanced.txt)	2m 3s
Slides (gnat_project_facility/standard_course.txt)	1m 14s
Slides (gnat_studio/course.txt)	1m 10s
Slides (toolchain/gnat_toolchain.txt)	1m 56s
Slides (spark_for_ada_programmers/course.txt)	1m 39s
	42m 49s

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