move llmware base directory

Problem: I'm running out of storage on my primary drive

Suggested fix: allow an environment variable to set the base path

Example Refactor: `llmware\llmware\configs.py`
- use LLMWARE_BASE_PATH environment variable to set `_base_fp`
- revert to using the existing USERPROFILE path if directory does not exist

Start in llmware\\llmware\\configs.py and inspect how _base_fp currently uses the USERPROFILE path. Implement the requested LLMWARE_BASE_PATH environment-variable behavior, retaining the existing USERPROFILE path when the configured directory does not exist. Done means the base directory can be moved through the environment variable without breaking the fallback.

Written by the indexing model from the issue text.