Add SPDX license identifier to all the .kt files.

[janiceferns02]

Contributor checklist

• This pull request is on a separate branch and not the main branch
• I have tested my code with the ./gradlew lintKotlin detekt test command as directed in the testing section of the contributing guide

---

Description

Replaced the existing license notice with the line: // SPDX-License-Identifier: AGPL-3.0-or-later to standardise license declarations across source files.

Related issue

• Adding a licence identifier to Kotlin files #301

[github-actions]

Thank you for the pull request!

The Scribe team will do our best to address your contribution as soon as we can. The following is a checklist for maintainers to make sure this process goes as well as possible. Feel free to address the points below yourself in further commits if you realize that actions are needed :)

If you're not already a member of our public Matrix community, please consider joining! We'd suggest using Element as your Matrix client, and definitely join the General and Android rooms once you're in. Also consider joining our bi-weekly Saturday dev syncs. It'd be great to have you!

Maintainer checklist

• The linting and formatting workflows within the PR checks do not indicate new errors in the files changed

• The CHANGELOG has been updated with a description of the changes for the upcoming release and the corresponding issue (if necessary)

[github-actions]

First PR Commit Check

• The commit messages for the remote branch should be checked to make sure the contributor's email is set up correctly so that they receive credit for their contribution
  - The contributor's name and icon in remote commits should be the same as what appears in the PR
  - If there's a mismatch, the contributor needs to make sure that the email they use for GitHub matches what they have for git config user.email in their local Scribe-Android repo (can be set with git config --global user.email "GITHUB_EMAIL")

[andrewtavis]

Haha so that's why you had the blank line there, @janiceferns02 :) Adding the blank lines back in 😊

[andrewtavis]

Thanks for the help here, @janiceferns02! Really appreciate it :) We have a similar issue for iOS in scribe-org/Scribe-iOS#528 if you had interest in doing that one too 😊