Issue #470: Add support for `host.id`, `host.name`, and other attributes as arrays in resource configuration

[NassimBtk]

This pull request includes several changes to the deserialization logic in the metricshub-agent project, focusing on handling multi-value attributes and updating resource configurations. The most important changes include modifications to the AttributesDeserializer and PostConfigDeserializer classes, as well as updates to the associated tests.

Deserialization Logic Improvements:

• AttributesDeserializer.java: Added the MULTI_VALUE_SEPARATOR constant to handle multi-value attributes during deserialization. Updated the deserialize method to use this separator. [1] [2]
• PostConfigDeserializer.java: Replaced the handling of multiple hosts with handling multiple resources, updated the logic to split multi-value attributes, and added methods to normalize protocol hostnames and determine attribute values. Deprecated the MULTI_HOST_ATTRIBUTE_KEY. [1] [2] [3] [4]

Test Updates:

• AgentContextTest.java: Updated test cases to reflect the new resource key format for multi-resource configurations.

• AttributesDeserializerTest.java: Modified the test to use the MULTI_VALUE_SEPARATOR constant and adjusted the expected results for multi-value attributes. [1] [2]

  Testing

Legacy host.names

host.name as array

Multiple attributes as array

host.name and protocol hostname as array