Better error output, and verusfmt before rustfmt (#23)

## Quick Comparison

(Running on an obviously broken input)

### Before:
<img width="487" alt="image"
src="https://github.com/jaybosamiya/verusfmt/assets/5683582/479605ec-8849-4c0f-b077-a4dc76d6b7ff">

### After:
<img width="949" alt="image"
src="https://github.com/jaybosamiya/verusfmt/assets/5683582/89a8eb18-86c5-4038-ba8f-b67dfc7277fd">


## Details
* run verusfmt formatting before doing rustfmt; this allows us to give
more precise error locations in case of parse failures; the two
formatters should otherwise not interact with each other anyways, so the
choice of which one first was not a particularly critical decision
anyways (iirc)
* switch from [`anyhow`](https://github.com/dtolnay/anyhow/) to
[`miette`](https://github.com/zkat/miette) to enable nicer outputs
* start reporting the file name for the parse failure (fixes #20)
* produce nicer error output along with context lines

Cargo.toml

@@ -5,16 +5,17 @@ edition = "2021"
 autoexamples = false
 
 [dependencies]
-anyhow = "1.0.71"
 clap = { version = "4.3.11", features = ["derive"] }
 fs-err = "2.9.0"
 insta = "1.30.0"
 itertools = "0.11.0"
+miette = { version = "5.10.0", features = ["fancy"] }
 pest = "2.0"
 pest_derive = "2.0"
 pretty = "0.12.1"
 regex = "1.9.6"
 similar = "2.2.1"
+thiserror = "1.0.52"
 tracing = "0.1.37"
 tracing-subscriber = { version = "0.3.17" }