NSFS | NC | Docs improvements

[romayalon]

Explain the changes

1. moved the standalone (with db) - docs/standalone.md → docs/dev_guide/standalone_with_db.md
2. moved the non-containerized design - [docs/nsfs-standalone.md → docs/design/NonContainerizedNSFSDesign.md
3. Main non containerized instructions -
   a. download instruction of nightly action build rpm
   b. added developer customization reference
   c. updated paths and versions
   d. removed old manual account creation from the s3 test example
   e. added health script output
   f. removed curl http test
4. added developer customization - describes different customizations & setting steps

Issues: Fixed #xxx / Gap #xxx

1. remove .env part from the guide & replace envs with config.json field in the customization guide after the new configuration structure discussion.
2. decide if UV_THREAD_POOL_SIZE and GPFS_LIB_PATH and other customizations should be included in the list as well.

Testing Instructions:

• Doc added/updated
• Tests added