Installer issues

[AlexSkrypnyk]

1. Demo comment is not removed from .env

################################################################################
#                                  DEMO                                        #
################################################################################

#-------------------------------------------------------------------------------
# Variables used to override project-specific values for demonstration purposes.
#
# This is to allow to demonstrate how Vortex works without asking users
# to perform any additional steps when trying out Vortex for the first time.
#
# Remove this section from your project when database download integration setup
# is finished.
#-------------------------------------------------------------------------------

2. URL should accept full URL with https://www.example.com and extract domain

3. Additionally process .env file to remove double empty lines.

4. Pre-built container image is not removed from .env when non-image DB download is selected

# Name of the pre-built container image.
# Uncomment to use an image with a DB data loaded into it.
# @see https://github.com/drevops/mariadb-drupal-data to seed your DB image.
# VORTEX_DB_IMAGE=

5. Drupal 10 was not replaced in readme.

6. Install file did not remove itself