Add option BUILD_ONLY to the build compile scripts (#4455)

* Rename default-build.sh -> build-tasks.sh

This commit is just a file rename without any
further code change before this script will be
refactored to improve build task structure
for partial building.

Refers to #4421

* Prepare build-tasks.sh for moving each build step to a dedicated function

This commit is an intermediate update to reflect
NO functional code changes of the particular
build steps before moving the unmodified code
into the appropriate function by copy/paste.
Only build_get_boot_sources() has slightly changed
to an appropriate if / fi structure.
Note: This .sh file is bash syntactically not correct.
The purpose of this commit is to leverage code review.

Refers to #4421

* Update build-tasks.sh function do_default() for filtered function calls

Function do_default():
  - Add $1 function parameter for filtering build tasks
    and assign this to local variable $_buildOnly
  - move "pseudo inline"-functions to the beginning of the script
  - replace the "inline functions" by filtered function calls
  - add BUILD_ONLY variable to the build epilog print

Refers to #4421

* Complete refactoring of build-tasks.sh for BUILD_ONLY support

- update indentation of functions build_get_boot_sources()
  and build_get_kernel_sources() to meet code style
- rename original function do_default() -> build_main()
- create new do_default() for backward compatibility and
  comment this one as deprecated
- call build_main "" from this deprecated do_default()
- cli-entrypoint.sh:
  - update call of do_default by build_main "${BUILD_ONLY}"

closes #4421

* Print final runtime as min:seconds

As with filtered build runtimes
may get below a minute, we would like
to get the runtime printed with seconds.

* Delete duplicate messages

* Fix the confusion of the choice of building the kernel

* Fix a typo in comment on do_default()

* Backward compatibility of KERNEL_ONLY and new BUILD_ONLY keys.

* interactive_config: replace KERNEL_ONLY on BUILD_ONLY

* Fix: Correct verification when an image is created

* Abort with error if BUILD_ONLY contains invalid build task names

- add function build_validate_buildOnly()
- call this function from build_main
- fix position of KERNEL_ONLY / BUILD_ONLY contradiction message
  (did log empty _buildOnly content all time)
- improve local variable names

* Improve final error message to list valid BUILD_ONLY task names

* Improve error message logging

- collect multiple invalid BUILD_ONLY task names in a single error message
- log final message for valid BUILD_ONLY task names on ext level
- simple exit with exit code 1 in case of error

* The RELEASE variable cannot be empty.

Additional conditions for checking RELEASE are unacceptable.

* Fix build_main() to use BUILD_ONLY inside instead of local var set from parameter $1

- build-tasks.sh:
  - build_main():
    - don't take parameter $1
    - replace usage of $_buildOnly by $BUILD_ONLY
    - added info messages on KERNEL_ONLY cases in case BUILD_ONLY was propagated
  - build_validate_buildOnly():
    - remove parameter $2
    - assign _buildOnly from global BUILD_ONLY accordingly
- cli-entrypoint.sh:
  - call build_main without parameter

* Choosing interactive_config if the goal is bootstrap

* fix: order of selection backward_compatibility_build_only

* Update function comments to match current state

- removed obsolete parameter of build_main call do_default()
- replaced :space: by :comma: in _kernel_buildOnly
  to leverage copy / paste for final repeatable command line
  printed after build

* Improve logic coding to filter build tasks

- build-tasks.sh:
  - added functions:
    - build_task_is_enabled()
    - build_task_one_of_is_enabled()
    - build_task_each_of_is_enabled()
  - updated existing build task filter logic
    to use function build_task_is_enabled
- config-prepare.sh, prepare-host.sh:
  - replaced existing build task filter logic
    to use function build_task_is_enabled

* Remove unused functions

- remove function build_task_one_of_is_enabled()
  and build_task_each_of_is_enabled()
  according to code review

Co-authored-by: The-going <48602507+The-going@users.noreply.github.com>

lib/functions/main/config-prepare.sh

@@ -86,6 +86,8 @@ function prepare_and_config_main_build_single() {
 
 	# if KERNEL_ONLY, KERNEL_CONFIGURE, BOARD, BRANCH or RELEASE are not set, display selection menu
 
+	backward_compatibility_build_only
+
 	interactive_config_ask_kernel
 
 	interactive_config_ask_board_list
@@ -110,11 +112,14 @@ function prepare_and_config_main_build_single() {
 
 	interactive_config_ask_branch
 
-	interactive_config_ask_release
+	build_task_is_enabled "bootstrap" && {
 
-	interactive_config_ask_desktop_build
+		interactive_config_ask_release
 
-	interactive_config_ask_standard_or_minimal
+		interactive_config_ask_desktop_build
+
+		interactive_config_ask_standard_or_minimal
+	}
 
 	#prevent conflicting setup
 	if [[ $BUILD_DESKTOP == "yes" ]]; then