Use global paths for macros

[CinchBlue]

Fixes #357

[CinchBlue]

Why does this fail? This was failing before I branched/forked off main:

error[E0308]: mismatched types
  --> metrics-observer/src/main.rs:32:40
   |
32 |     let stdout = AlternateScreen::from(stdout);
   |                  --------------------- ^^^^^^ expected struct `AlternateScreen`, found struct `MouseTerminal`
   |                  |
   |                  arguments to this function are incorrect
   |
   = note: expected struct `AlternateScreen<_>`
              found struct `MouseTerminal<RawTerminal<Stdout>>`
note: associated function defined here
  --> /rustc/9eb3afe9ebe9c7d2b84b71002d44f4a0edac95e0/library/core/src/convert/mod.rs:548:8

For more information about this error, try `rustc --explain E0308`.
error: could not compile `metrics-observer` due to previous error
warning: build failed, waiting for other jobs to finish...
error: could not compile `metrics-observer` due to previous error
error: process didn't exit successfully: `/home/runner/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/bin/cargo build --all-targets --manifest-path metrics-observer/Cargo.toml --no-default-features` (exit status: 101)

[tobz]

Looks like a bunch of the macro tests are still broken but I'm going to merge this anyways and I'll take care of those as I work on some other stuff on the backlog.

[tobz]

Released as metrics-macros@v0.7.0 (transitively via metrics@v0.21.0).

Thanks again for your contribution!