Remove commons-validator, replace its sole usage with guava's InetAddresses.isInetAddress

[krzysztof-tobola]

This is a proposal to remove commons-validator dependency and declare Guava explicitly in java-spiffe-core.
This is because of unmaintained transitional dependencies that cause security scanners to raise alerts.

• The commons-validator InetAddressValidator.getInstance().isValid(..) in Address.validateTcpAddress is replaced with Guava's InetAddresses.isInetAddress(..).

• The following dependencies are removed:

  +--- commons-validator:commons-validator:1.11.0
  |    +--- commons-beanutils:commons-beanutils:1.11.0
  |    |    +--- commons-logging:commons-logging:1.3.5 -> 1.4.0
  |    |    \--- commons-collections:commons-collections:3.2.2
  |    +--- commons-digester:commons-digester:2.1
  |    +--- commons-logging:commons-logging:1.4.0
  |    \--- commons-collections:commons-collections:3.2.2
  

No public API change. Address validation logic should remain intact, both methods check for a literal IPv4/IPv6 address without a DNS lookup, and reject hostnames, all test cases still pass.

Published POMs change: all three modules drop commons-validator, and java-spiffe-core gains com.google.guava:guava:33.6.0-jre at runtime scope.