Chore/improve GH action pipelines

[winqus]

Slow pipes. Improve caching

ChatGPT suggested Backend CI actions script for improved caching:

name: Backend CI

on:
  pull_request:
    paths:
      - 'ntx-backend-nestjs/**'

jobs:
  backend:
    name: Backend Build and Test
    runs-on: ubuntu-latest

    steps:
      - name: Checkout repository
        uses: actions/checkout@v3

      - name: Set up Node.js
        uses: actions/setup-node@v3
        with:
          node-version: '20'
          cache: 'npm'
          cache-dependency-path: 'ntx-backend-nestjs/package-lock.json'

      - name: Install dependencies
        working-directory: ntx-backend-nestjs
        run: npm ci

      - name: Run lint
        working-directory: ntx-backend-nestjs
        run: npm run lint

      - name: Build
        working-directory: ntx-backend-nestjs
        run: npm run build

      - name: Run tests
        working-directory: ntx-backend-nestjs
        run: npm run test-ci