FINERACT-2748: Tax Group – Adjust error message

[rymghosn]

Submitting a Tax Group without any tax components previously failed only on the generic integerGreaterThanZero check, without a clear message.
This adds an explicit validation error (validation.msg.at.least.one.tax.component.required) with a user-friendly message ("Please add at least
one Tax Component before submitting the Tax Group.") when the taxComponents array is empty.

Added an integration test (TaxesTest#createTaxGroupWithoutTaxComponent_shouldReturnValidationError) covering the new validation path.
PR:(https://issues.apache.org/jira/browse/FINERACT-2748)

[adamsaghy]

What went wrong:
Execution failed for task ':fineract-tax:spotlessJavaCheck'.

The following files had format violations:
src/main/java/org/apache/fineract/portfolio/tax/serialization/TaxValidator.java
@@ -193,13 +193,8 @@
········if·(topLevelJsonElement.get(TaxApiConstants.taxComponentsParamName).isJsonArray())·{
············final·JsonArray·array·=·topLevelJsonElement.get(TaxApiConstants.taxComponentsParamName).getAsJsonArray();
············if·(array.isEmpty())·{
-················dataValidationErrors.add(
-························ApiParameterError.parameterError(
-································"validation.msg.at.least.one.tax.component.required",
-································"Please·add·at·least·one·Tax·Component·before·submitting·the·Tax·Group.",
-································TaxApiConstants.taxComponentsParamName
-························)
-················);
+················dataValidationErrors.add(ApiParameterError.parameterError("validation.msg.at.least.one.tax.component.required",
+························"Please·add·at·least·one·Tax·Component·before·submitting·the·Tax·Group.",·TaxApiConstants.taxComponentsParamName));
············}
············baseDataValidator.reset().parameter(TaxApiConstants.taxComponentsParamName).value(array.size()).integerGreaterThanZero();
[Incubating] Problems report is available at: file:///home/runner/work/fineract/fineract/build/reports/problems/problems-report.html
············for·(int·i·=·1;·i·<=·array.size();·i++)·{
Run './gradlew :fineract-tax:spotlessApply' to fix these violations.