Move stitching out of legacy scaling_factors/ to avoid confusion

[backmari]

Description of work:

The modules in the folder scaling_factors/ are unrelated to stitching scaling factors. To avoid confusion, move the stitching functions into a separate module stitching.py.

Check all that apply:

• updated documentation
• Source added/refactored
• Added unit tests
• Added integration tests
• Verified that tests requiring the /SNS and /HFIR filesystems pass without fail

References:

• Links to IBM EWM items:
• Links to related issues or pull requests:

⚠️ Manual test for the reviewer

(Instructions for testing here)

Check list for the reviewer

• best software practices
  • clearly named variables (better to be verbose in variable names)
  • code comments explaining the intent of code blocks
• All the tests are passing
• The documentation is up to date
• code comments added when explaining intent