[variant] Group each variant per boards type

As the number of variants continues to grow and in order to
facilitate navigation, they have been grouped in a sub-folder
corresponding to each boards entry.

Signed-off-by: Frederic Pillon <frederic.pillon@st.com>

Author: fpistm

boards.txt

@@ -109,7 +109,7 @@ build.opt.path={build.path}/sketch/{build.opt.name}
 extras.path={build.system.path}/extras
 
 # Create empty {build.opt} if not exists in the output sketch dir and force include of SrcWrapper library
-recipe.hooks.prebuild.1.pattern="{extras.path}/prebuild.sh" "{build.path}" "{build.source.path}" 
+recipe.hooks.prebuild.1.pattern="{extras.path}/prebuild.sh" "{build.path}" "{build.source.path}"
 recipe.hooks.prebuild.1.pattern.windows="{runtime.tools.STM32Tools.path}/tools/win/busybox.exe" sh "{extras.path}/prebuild.sh" "{build.path}" "{build.source.path}"
 
 # compile patterns
@@ -140,7 +140,7 @@ build.preferred_out_format=bin
 
 ## Save binary
 recipe.output.tmp_file={build.project_name}.{build.preferred_out_format}
-recipe.output.save_file={build.project_name}.{build.variant}.{build.preferred_out_format}
+recipe.output.save_file={build.project_name}.{build.board}.{build.preferred_out_format}
 
 ## Compute size
 recipe.size.pattern="{compiler.path}{compiler.size.cmd}" -A "{build.path}/{build.project_name}.elf"
@@ -188,7 +188,7 @@ tools.hid_upload.path.macosx={runtime.tools.STM32Tools.path}/tools/macosx
 tools.hid_upload.path.linux={runtime.tools.STM32Tools.path}/tools/linux
 tools.hid_upload.upload.params.verbose=-d
 tools.hid_upload.upload.params.quiet=n
-tools.hid_upload.upload.pattern="{path}/{cmd}" "{build.path}/{build.project_name}.bin" {serial.port.file}                                                                                                                             
+tools.hid_upload.upload.pattern="{path}/{cmd}" "{build.path}/{build.project_name}.bin" {serial.port.file}
 
 # Upload using Maple bootloader over DFU
 tools.maple_upload.cmd=maple_upload.sh
@@ -207,4 +207,4 @@ tools.remoteproc_gen.busybox.windows={path}/win/busybox.exe
 tools.remoteproc_gen.script=run_arduino_gen.sh
 tools.remoteproc_gen.upload.params.verbose=
 tools.remoteproc_gen.upload.params.quiet=
-tools.remoteproc_gen.upload.pattern="{busybox}" sh "{path}/{script}" generate "{build.path}/{build.project_name}.elf" "{build.path}/run_arduino_{build.project_name}.sh" 
+tools.remoteproc_gen.upload.pattern="{busybox}" sh "{path}/{script}" generate "{build.path}/{build.project_name}.elf" "{build.path}/run_arduino_{build.project_name}.sh"