[FEATURE] Support custom dimension for mem0 OpenSearch integration

[andy-k-improving]

Problem Statement

This is a follow up issue from #262, which during the PR review discussion, we realized that the dimensions value for OpenSearch is hard-coded and this will be a problem, when user supply any embedding model with output != 1024 dimensions.

Hence this is a feature request for it, to have the dimension value also read from environment variable, and only fallback to 1024 if nothing specified.

Proposed Solution

Update the also read dimension value from ENV, and fallback to 1024 if nothing specified.

Use Case

When user supply a custom embedding model which produce != 2014 dimensions for embedding.

Alternatives Solutions

No response

Additional Context

No response