Decompress files for config_install

Problem/Motivation

Compressed files, binaries, and databases are difficult to maintain and inspect.

This issue is to address:
./core/tests/fixtures/config_install/multilingual.tar.gz
./core/tests/fixtures/config_install/testing_config_install.tar.gz
./core/tests/fixtures/config_install/testing_config_install_no_config.tar.gz

Background information

This was first reported to the Drupal security team who determined this could be a public followup.

• security.drupal.org private issue: https://security.drupal.org/node/180341
  (included for reference. Please do not report access denied as an error.)

Steps to reproduce

Proposed resolution

Remaining tasks

./core/tests/fixtures/config_install/multilingual.tar.gz
./core/tests/fixtures/config_install/testing_config_install.tar.gz
./core/tests/fixtures/config_install/testing_config_install_no_config.tar.gz

User interface changes

API changes

Data model changes

Release notes snippet