Upgrade gradle to v7.3

See merge request !44

Fix small setup token issues identified in review

Closes #50

See merge request !39

Properly nulls settings and adds a test that setup token can't be used anymore

Add shortcut methods Database#read() and #write()

Closes #67

See merge request !40

API endpoint for checking mailbox status

Closes #70

See merge request !38

Resolve "Check Java code style using CI"

Closes #71

See merge request !37

API endpoint for wiping the mailbox

Closes #62

See merge request !33

Add do-not-kill-lib from Briar and show its fragment whenever needed

Closes #38

See merge request !34

Encode QR code for pairing

Closes #48

See merge request !35

Store single-use auth token and implement setup API endpoint

Closes #50 and #42

See merge request !30

Fix integration test after merge race condition

See merge request !32

Implement contact management API

Closes #58, #57, #56, #45, and #4

See merge request !24

Implement file management API

Closes #55, #54, #53, #52, and #51

See merge request !28