Refactor: LaTeX processing in external Docker container

[b0ink]

Depends on thoth-tech/doubtfire-deploy#13
Feasibility document: thoth-tech/documentation#534

Description

This update moves LaTeX processing into a dedicated TeX Live container. Instead of running lualatex from the latex_config, the latex_run.sh script is executed after being copied into the working directory (along with other input files such as input.tex and jupynotex.py).

latex_run.sh then runs sudo docker exec ... into the TeX Live container and executes latex_build.sh, which is in charge of running the lualatex commands.

latex_run.sh relies on two environment variables to be set:

LATEX_CONTAINER_NAME=formatif-texlive-container # Name of the TeX Live container
LATEX_BUILD_PATH=/texlive/shell/latex_build.sh # Path on the TeX Live container

The render_to_string() method that renders the PDFs is now wrapped in a generate_pdf() method defined in latex_helper.rb, ensuring the environment variables are set before executing latex_run.sh via render_to_string.

Type of change

• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

How Has This Been Tested?

• Use the modified docker-compose from Refactor: External TeX Live docker container doubtfire-deploy#13
• If you encounter issues with the setup, remove any previous Docker devcontainer builds and volumes.
• Run rake test in doubtfire-api to validate PDF generation.
• Optionally, run rake db:simulate_signoff which will create several tasks and render them with lualatex.
• You can also manually create a portfolio when logged in as a student, upload different test files, click "Create my portfolio", then run doubtfire-api/lib/shell/generate_pdfs.sh

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation if appropriate
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• I have created or extended unit tests to address my new additions
• New and existing unit tests pass locally with my changes
• Any dependent changes have been merged and published in downstream modules

TODO:

• Remove previous texlive-install.sh and texlive.profile scripts
• Add TeX Live service to docker-compose in doubtfire-api

[JackSCarroll]

This looks good and latex works as intended.
Old function calls have been replaced with new functions correctly.
I like that you've added the env var checks in latex_helper.rb.