Patch that fixes several bugs in metadata validation and submission

[jessicarowell]

Description

1. Fix typo in nf-schema (to a liftoff param name)
2. Fill in vadr_models param in nextflow.config/test config (this needs to be addressed later)
3. Fix metadata validation to accept any valid string for populate_fields() function
4. Make Title optional in BioSample submission xml
5. Make fasta-file optional in update_submission module (if not gb, not required)
6. Fix submission python script to check for GB flag in update_submission fx

Checklist

Go Through Checklist Below and Place A ✔️ (X Inside the Box) if Completed

General Checks

• [] Have you run appropriate tests (unit/integration/end-to-end) to check logic across run environments (Conda/Docker/Singularity on Scicomp/AWS/NF Tower/Local)?

Only tested on SciComp

• Have you conducted proper linting procedures?

  • Numpy formatted docstrings for functions
  • Comments explaining lines of code
  • Consistent and intuitive naming conventions for variables, functions, classes, methods, attributes, and scripts
  • Single empty line between class functions, two lines between non-class functions, and two lines between imports and code body
  • Camel case formatting for class names

• Have you updated existing documentation (README.md, etc.) or created new ones within docs?

No updates needed

CDC Checks

• Did you check for sensitive data, and remove any?
• If you added or modified HTML, did you check that it was 508 compliant?

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