feat: allow boards to change debug support via FQBN options

"debug.executable" must be present AND non-empty for debugging to be
supported, allowing board overrides. Also, use the same logic in the
details view and in the actual debug command implementation.

Author: pillo79

Diff for: commands/board/details.go

@@ -23,6 +23,7 @@ import (
 	"github.com/arduino/arduino-cli/arduino/utils"
 	"github.com/arduino/arduino-cli/commands/internal/instances"
 	rpc "github.com/arduino/arduino-cli/rpc/cc/arduino/cli/commands/v1"
+	"github.com/arduino/go-properties-orderedmap"
 )
 
 // Details returns all details for a board including tools and HW identifiers.
@@ -64,9 +65,14 @@ func Details(ctx context.Context, req *rpc.BoardDetailsRequest) (*rpc.BoardDetai
 		details.BuildProperties, _ = utils.ExpandBuildProperties(details.GetBuildProperties())
 	}
 
-	details.DebuggingSupported = boardProperties.ContainsKey("debug.executable") ||
-		boardPlatformRelease.Properties.ContainsKey("debug.executable") ||
-		(boardRefPlatform != nil && boardRefPlatform.Properties.ContainsKey("debug.executable"))
+	toolProperties := properties.NewMap()
+	if boardRefPlatform != nil {
+		toolProperties.Merge(boardRefPlatform.Properties)
+	}
+	toolProperties.Merge(boardPlatform.Properties)
+	toolProperties.Merge(boardPlatform.RuntimeProperties())
+	toolProperties.Merge(boardProperties)
+	details.DebuggingSupported = toolProperties.ContainsKey("debug.executable") && toolProperties.Get("debug.executable") != ""
 
 	details.Package = &rpc.Package{
 		Name:       boardPackage.Name,

Diff for: commands/debug/debug_info.go

@@ -134,7 +134,7 @@ func getDebugProperties(req *rpc.GetDebugConfigRequest, pme *packagemanager.Expl
 		debugProperties.Set(k, toolProperties.ExpandPropsInString(v))
 	}
 
-	if !debugProperties.ContainsKey("executable") {
+	if !debugProperties.ContainsKey("executable") || debugProperties.Get("executable") == "" {
 		return nil, &arduino.FailedDebugError{Message: tr("Debugging not supported for board %s", req.GetFqbn())}
 	}
 

Diff for: docs/UPGRADING.md

@@ -2521,6 +2521,8 @@ debug.server.openocd.scripts_dir={runtime.tools.openocd-0.10.0-arduino7.path}/sh
 debug.server.openocd.script={runtime.platform.path}/variants/{build.variant}/{build.openocdscript}
 ```
 
+The `debug.executable` key must be present and non-empty for debugging to be supported.
+
 The `debug.server.XXXX` subkeys are optional and also "free text", this means that the configuration may be extended as
 needed by the specific server. For now only `openocd` is supported. Anyway, if this change works, any other kind of
 server may be fairly easily added.