Add AWS IAM Authentication to `EnvironmentVaultConfiguration`

[missedone]

spring-vault/spring-vault-core/src/main/java/org/springframework/vault/config/EnvironmentVaultConfiguration.java

Lines 250 to 273 in 26a77a2

	public ClientAuthentication clientAuthentication() {
	String authentication = getProperty("vault.authentication", AuthenticationMethod.TOKEN.name()).toUpperCase()
	.replace('-', '_');
	AuthenticationMethod authenticationMethod = AuthenticationMethod.valueOf(authentication);
	switch (authenticationMethod) {
	case TOKEN:
	return tokenAuthentication();
	case APPID:
	return appIdAuthentication();
	case APPROLE:
	return appRoleAuthentication();
	case AWS_EC2:
	return awsEc2Authentication();
	case AZURE:
	return azureMsiAuthentication();
	case CERT:
	return new ClientCertificateAuthentication(restOperations());
	case CUBBYHOLE:
	return cubbyholeAuthentication();
	case KUBERNETES:

EnvironmentVaultConfiguration supports AWS EC2 today, which is good, can you also add support for AWS IAM?

[mp911de]

Feel free to submit a pull request.

[missedone]

sure, done #765