refactor!: update Kind field to Type in source code (#2312)

Update source code `Kind` to `Type`. It's only changes within our code.
Changes to yaml tag (that will affect users) will be done in later PRs.

This is a breaking change since it updates telemetry's span attribute
from `source_kind` to `source_type`.

Related #817

Future updates will include: 
* Updating a preprocessing function to convert config file from v1 to v2
* Update unmarshal function for ToolsFile to convert config file (test
will fail since the yaml tag is not yet updated).
* Update yaml tag (test will pass).

internal/tools/cloudsql/cloudsqlcreateusers/cloudsqlcreateusers.go

@@ -29,7 +29,7 @@ const kind string = "cloud-sql-create-users"
 
 func init() {
 	if !tools.Register(kind, newConfig) {
-		panic(fmt.Sprintf("tool kind %q already registered", kind))
+		panic(fmt.Sprintf("tool type %q already registered", kind))
 	}
 }
 
@@ -50,7 +50,7 @@ type compatibleSource interface {
 // Config defines the configuration for the create-user tool.
 type Config struct {
 	Name         string   `yaml:"name" validate:"required"`
-	Kind         string   `yaml:"kind" validate:"required"`
+	Type         string   `yaml:"kind" validate:"required"`
 	Source       string   `yaml:"source" validate:"required"`
 	Description  string   `yaml:"description"`
 	AuthRequired []string `yaml:"authRequired"`
@@ -59,8 +59,8 @@ type Config struct {
 // validate interface
 var _ tools.ToolConfig = Config{}
 
-// ToolConfigKind returns the kind of the tool.
-func (cfg Config) ToolConfigKind() string {
+// ToolConfigType returns the kind of the tool.
+func (cfg Config) ToolConfigType() string {
 	return kind
 }
 
@@ -120,7 +120,7 @@ func (t Tool) ToConfig() tools.ToolConfig {
 
 // Invoke executes the tool's logic.
 func (t Tool) Invoke(ctx context.Context, resourceMgr tools.SourceProvider, params parameters.ParamValues, accessToken tools.AccessToken) (any, error) {
-	source, err := tools.GetCompatibleSource[compatibleSource](resourceMgr, t.Source, t.Name, t.Kind)
+	source, err := tools.GetCompatibleSource[compatibleSource](resourceMgr, t.Source, t.Name, t.Type)
 	if err != nil {
 		return nil, err
 	}
@@ -170,7 +170,7 @@ func (t Tool) Authorized(verifiedAuthServices []string) bool {
 }
 
 func (t Tool) RequiresClientAuthorization(resourceMgr tools.SourceProvider) (bool, error) {
-	source, err := tools.GetCompatibleSource[compatibleSource](resourceMgr, t.Source, t.Name, t.Kind)
+	source, err := tools.GetCompatibleSource[compatibleSource](resourceMgr, t.Source, t.Name, t.Type)
 	if err != nil {
 		return false, err
 	}

internal/tools/cloudsql/cloudsqlcreateusers/cloudsqlcreateusers_test.go

@@ -46,7 +46,7 @@ func TestParseFromYaml(t *testing.T) {
 			want: server.ToolConfigs{
 				"create-user": cloudsqlcreateusers.Config{
 					Name:         "create-user",
-					Kind:         "cloud-sql-create-users",
+					Type:         "cloud-sql-create-users",
 					Source:       "my-source",
 					Description:  "some description",
 					AuthRequired: []string{},