Add support for `Charset` to value code generator

[snicoll]

The spring batch smoke test is failing (which looks new) because Charset is not supported:

Exception in thread "main" java.lang.IllegalArgumentException: Failed to generate code for 'UTF-8' with type sun.nio.cs.UTF_8
        at org.springframework.beans.factory.aot.BeanDefinitionPropertyValueCodeGenerator.generateCode(BeanDefinitionPropertyValueCodeGenerator.java:91)
        at org.springframework.beans.factory.aot.BeanDefinitionPropertiesCodeGenerator.addPropertyValues(BeanDefinitionPropertiesCodeGenerator.java:182)
        at org.springframework.beans.factory.aot.BeanDefinitionPropertiesCodeGenerator.generateCode(BeanDefinitionPropertiesCodeGenerator.java:128)
        at org.springframework.beans.factory.aot.DefaultBeanRegistrationCodeFragments.generateSetBeanDefinitionPropertiesCode(DefaultBeanRegistrationCodeFragments.java:145)
        at org.springframework.beans.factory.aot.BeanRegistrationCodeGenerator.generateCode(BeanRegistrationCodeGenerator.java:86)
        at org.springframework.beans.factory.aot.BeanDefinitionMethodGenerator.lambda$generateBeanDefinitionMethod$2(BeanDefinitionMethodGenerator.java:147)
        at org.springframework.aot.generate.GeneratedMethod.<init>(GeneratedMethod.java:54)
        at org.springframework.aot.generate.GeneratedMethods.add(GeneratedMethods.java:93)
        at org.springframework.aot.generate.GeneratedMethods.add(GeneratedMethods.java:80)
        at org.springframework.beans.factory.aot.BeanDefinitionMethodGenerator.generateBeanDefinitionMethod(BeanDefinitionMethodGenerator.java:141)
        at org.springframework.beans.factory.aot.BeanDefinitionMethodGenerator.generateBeanDefinitionMethod(BeanDefinitionMethodGenerator.java:107)
        at org.springframework.beans.factory.aot.BeanRegistrationsAotContribution.lambda$generateRegisterMethod$2(BeanRegistrationsAotContribution.java:83)