Use drupal namespace in composer.

[rosiel]

GitHub Issue: Islandora/documentation#2270

• Other Relevant Links (Google Groups discussion, related pull requests,
  Release pull requests, etc.)

https://groups.google.com/g/islandora/c/brFsDlPRwrI/m/JcgM29OwAAAJ

What does this Pull Request do?

Changes the name of the module.

What's new?

• changes islandora/islandora_mirador to drupal/islandora_mirador in composer.json.

How should this be tested?

See Islandora/controlled_access_terms#130 for testing notes though this module has no tests (hence also the removal of the testing badge).

Documentation Status

• Does this change existing behaviour that's currently documented?
• Does this change require new pages or sections of documentation?
• Who does this need to be documented for?
• Associated documentation pull request(s): ___ or documentation issue ___

Additional Notes:

Any additional information that you think would be helpful when reviewing this
PR.

Interested parties

Tag (@ mention) interested parties or, if unsure, @Islandora/committers

[aOelschlager]

Approved in tech meeting.