Add linter and github actions

[DanielMontesGuerrero]

Add eslint and pretierr to project.

• Run npm run lint to check for lint errors
• Run npm run lint -- --fix to auto fix errors

Added two github actions:

• Build: triggers a remote build of the app to ensure it builds succesfully
• Lint: checks for linter errors in the code

Solved some linter errors.

Note: Run npm install after pulling this changes

close #18