Support leading-dot suffixes in NO_PROXY

[afarber]

Motivation and Context

Fixes #5573.

NO_PROXY commonly uses a leading-dot domain suffix such as .company.internal. The SDK accepted *.company.internal, but not the equivalent leading-dot form.

Modifications

• Normalize leading-dot suffixes in the NO_PROXY environment variable to the existing wildcard form.
• Add parsing and Apache proxy-route tests.
• Document leading-dot suffix support in the HTTP client proxy configuration Javadocs.
• Add a changelog entry.

Testing

Ran the affected utility tests:

./mvnw -pl :utils -Dtest=SdkHttpUtilsTest,ProxyConfigurationTest test

Ran the Apache proxy tests:

./mvnw -pl :apache-client -am -Dcheckstyle.skip=true -Dspotbugs.skip=true -Dtest=ApacheHttpProxyTest,SdkProxyRoutePlannerTest -Dsurefire.failIfNoSpecifiedTests=false test

Both commands succeeded.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)

Checklist

• I have read the CONTRIBUTING (https://github.com/aws/aws-sdk-java-v2/blob/master/CONTRIBUTING.md) document
• Local run of mvn install succeeds
• My code follows the code style of this project
• My change requires a change to the Javadoc documentation
• I have updated the Javadoc documentation accordingly
• I have added tests to cover my changes
• All new and existing tests passed
• I have added a changelog entry.
• My change is to implement 1.11 parity feature and I have updated LaunchChangelog
  (https://github.com/aws/aws-sdk-java-v2/blob/master/docs/LaunchChangelog.md)

License

• I confirm that this pull request can be released under the Apache 2 license