Consider logging missing `code_challenge` when PKCE is required

[sjohnr]

spring-authorization-server/oauth2-authorization-server/src/main/java/org/springframework/security/oauth2/server/authorization/authentication/CodeVerifierAuthenticator.java

Lines 97 to 99 in 27a893f

	if (!StringUtils.hasText(codeChallenge)) {
	if (registeredClient.getClientSettings().isRequireProofKey()) {
	throwInvalidGrant(PkceParameterNames.CODE_CHALLENGE);

We should consider adding a log entry at DEBUG level in CodeVerifierAuthenticator for this case. This would allow the logging level to be tuned specifically for this logging.