Use anyhow more idiomatically (#31052)

https://github.com/zed-industries/zed/issues/30972 brought up another
case where our context is not enough to track the actual source of the
issue: we get a general top-level error without inner error.

The reason for this was `.ok_or_else(|| anyhow!("failed to read HEAD
SHA"))?; ` on the top level.

The PR finally reworks the way we use anyhow to reduce such issues (or
at least make it simpler to bubble them up later in a fix).
On top of that, uses a few more anyhow methods for better readability.

* `.ok_or_else(|| anyhow!("..."))`, `map_err` and other similar error
conversion/option reporting cases are replaced with `context` and
`with_context` calls
* in addition to that, various `anyhow!("failed to do ...")` are
stripped with `.context("Doing ...")` messages instead to remove the
parasitic `failed to` text
* `anyhow::ensure!` is used instead of `if ... { return Err(...); }`
calls
* `anyhow::bail!` is used instead of `return Err(anyhow!(...));`

Release Notes:

- N/A

crates/extension/src/extension.rs

@@ -8,7 +8,7 @@ use std::path::{Path, PathBuf};
 use std::sync::Arc;
 
 use ::lsp::LanguageServerName;
-use anyhow::{Context as _, Result, anyhow, bail};
+use anyhow::{Context as _, Result, bail};
 use async_trait::async_trait;
 use fs::normalize_path;
 use gpui::{App, Task};
@@ -173,7 +173,7 @@ pub fn parse_wasm_extension_version(
     //
     // By parsing the entirety of the Wasm bytes before we return, we're able to detect this problem
     // earlier as an `Err` rather than as a panic.
-    version.ok_or_else(|| anyhow!("extension {} has no zed:api-version section", extension_id))
+    version.with_context(|| format!("extension {extension_id} has no zed:api-version section"))
 }
 
 fn parse_wasm_extension_version_custom_section(data: &[u8]) -> Option<SemanticVersion> {