[feat](api): add clients generated from openapi specs and use them fetch busroutelines

[jumpy-cat]

Description

Been working on end-to-end typesafety between the frontend and the backend, this PR adds the beginnings of that and trials it on the getAllRoutes and getAllRideRoutes routes that I needed to change anyway (moving the logic to the backend, also in this PR, see #98).

To run the frontend you will need to define an extra environment variable BACKEND_OPENAPI_URL, which would have a value similar to what you'd set BACKEND_URL to but without the extra /mbus/api/v3 at the end. Note that the url would have to point at a backend that matches the openapi spec (v2 of the mock backend should work). You will also have to generate the clients first, the ci file should have an up to date version of the commands needed.

It should look something like this (full clean & regenerate):

rm -rf lib/backend
dart run build_runner clean
dart run swagger_parser
dart run build_runner build

Type of Change

• New feature (feat)
• Bug fix (fix)
• Refactor / code improvement
• Dependency / build update
• Documentation
• Other (explain)

Related Issues

Prereq of how I'd like to do #98
Depends on mbusdev/mbus-backend-dev#47

Changes Made

• Flutter:
  • I am on a newer version which resulted in some migration stuff + having to manually update a dependency to get things working
  • updated the blue bus and ride clients to use the new generated client for fetchRoutes, also remove the parsing logic as thats in the backend now
  • added fromBackend methods to the model types that need it
  • add dependencies and config for client generation
  • CI that generates the clients & used flutter analyze to check for errors (should be combined w/ the other ci work when possible)
• Backend (TypeScript):
  • see feat: modify /plan-journey so it returns bus polylines mbus-backend-dev#47, feat(api): create request validation & openapi spec generation library mbus-backend-dev#46
• Firebase / Shared:
  • find openapi specs at https://docs.mb.thething.fyi (specifically https://docs.mb.thething.fyi/refs/heads/mock-backend-2/openapi/spec.json)

Testing Done

Flutter:

• Tested on:
  • iOS Simulator
  • Android Emulator (I uncommented a line to reenable the base routes layer and confirmed they still show up)
  • Physical device

Screenshots / Demo (if UI or notification change)

routes still show up! (using locally running backend TODO: test with mock v2)

Checklist

• Commit messages follow Conventional Commits
• PR title follows [type](scope): short description
• PR target branch is not main and is our current working update branch (e.g. maizebus2.1)
• No print() / debugPrint() / console.log() left in production code
• Secrets / keys not committed