Issue #3002515 by RohitRawat676: Coding standards

config/schema/field_validation.schema.yml

field_validation.module

src/Entity/FieldValidationRuleSet.php

src/FieldValidationRuleBase.php

src/Form/FieldValidationRuleAddForm.php

src/Form/FieldValidationRuleFormBase.php

...in/FieldValidationRule/EqualValuesFieldValidationRule.php

...ugin/FieldValidationRule/ItemCountFieldValidationRule.php

src/Plugin/FieldValidationRule/UrlFieldValidationRule.php

.../FieldValidationRule/ItemCountFieldValidationRuleTest.php

...FieldValidationRule/MatchFieldFieldValidationRuleTest.php

...Plugin/FieldValidationRule/UrlFieldValidationRuleTest.php