fix(dbus): fail if cannot be primary notification server

[kgilmer]

Addresses #87

Description

See #87 for details

Motivation and Context

Prevents the server from starting but doing nothing in the case that another service is primary for this D-Bus name

How Has This Been Tested?

Before change, running Regolith desktop on Ubuntu 23.04. By default the rofication demon holds the notification name in D-Bus:

$ cargo run
   Compiling runst v0.1.4 (/home/kgilmer/dev/repos/runst)
    Finished dev [unoptimized + debuginfo] target(s) in 3.20s
     Running `target/debug/runst`
2023-08-06T22:27:02.576823Z  INFO runst: starting

However runst does not show notifications with notify-send.

After change, program aborts:

$ cargo run
...
Running `target/debug/runst`
2023-08-06T22:18:40.543262Z  INFO runst: starting
thread '<unnamed>' panicked at 'failed to register D-Bus notification handler: InitializationError("Not primary D-Bus notification server, is another running?")', src/lib.rs:85:14
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
Aborted (core dumped)

Additionally, killing the name holder, then running runst, results in showing notifications with notify-send. (Note: I shortened the name of the error type after running the above test)

Screenshots / Logs (if applicable)

unnecessary

Types of Changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation (no code change)
• Refactor (refactoring production code)
• Other

Checklist:

• My code follows the code style of this project.
• I have updated the documentation accordingly.
• I have formatted the code with rustfmt.
• I checked the lints with clippy.
• [-] I have added tests to cover my changes.
  Unclear how a unit test could be added here without bigger changes
• All new and existing tests passed.

[orhun]

This is great, thank you! 💖