The yarn.lock file speed-ups an initial set-up but freezes the registry
URL, which can be different in the ~/.npmrc file when developing in a
company.

Markdown formatting, typos.

Makes the repository handle file line endings.
This helps to make it cross-platform, asserting some files are Unix-ended.

Uses the prefeed name of the Compose specification.

Changes:
- Removes the deprecated "version" field,
- Adds a toplevel "name" field (prefix of container names nad network),
- Adds a toplevel "network" field, with a common "timesketch-dev"
  network,
- Removes container names (depends on and toplevel name and service
  names),
- Do not bind to the 127.0.0.1 interface only (0.0.0.0),
- Removes useless "links" (common network),
- Refactors environment variables to don't use a YAML array,
- Removes "restart" fields to detect undesired crashes in development,
- Binds ports of other services to the host (opensearch, redis).

Adds .gitignore files.
Dramatically improves an image build in a development context.

Adapts the list to the latest version of the repository:
- Fixes moved ones,
- Deletes removed ones.

Changes are:
- Allows Docker image builds in a restricted company context (limited
  access to remote Ubuntu, Python or Node repositories) using variables,
- Centralizes variables in a .env file (not versioned),
- Adds a .env.template file as .env template with predefined variables,
- Use a distinct directory for every service dependencies,
- Use named volumes to avoid anonymous ones (PostgreSQL, Redis and
  Prometheus),
- Use a per-service environment file,
- Simplifies how development configuration files are transferred to
  Timesketch,
- Simplifies manipulation of containers using Compose CLI instead of
  the Docker one,
- Simplify and optimizes the Timesketch entrypoint,
- Updates the Bash scripts to start frontend-ng,
- Updates related documentation.

Use named volumes in Compose development

PostgreSQL, Redis and Prometheus declare volumes in their Dockerfile.
This leads to anonymous volume creations if they are not declared in
Compose.

Avoids using the system environment.

For now, there is no setting to switch with previous behaviour.