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/auto_update_helper/src/auto_update_helper.rs

@@ -22,7 +22,7 @@ mod windows_impl {
 
     use super::dialog::create_dialog_window;
     use super::updater::perform_update;
-    use anyhow::{Context, Result};
+    use anyhow::{Context as _, Result};
     use windows::{
         Win32::{
             Foundation::{HWND, LPARAM, WPARAM},

crates/auto_update_helper/src/updater.rs

@@ -4,7 +4,7 @@ use std::{
     time::{Duration, Instant},
 };
 
-use anyhow::{Context, Result};
+use anyhow::{Context as _, Result};
 use windows::Win32::{
     Foundation::{HWND, LPARAM, WPARAM},
     System::Threading::CREATE_NEW_PROCESS_GROUP,
@@ -124,9 +124,7 @@ pub(crate) fn perform_update(app_dir: &Path, hwnd: Option<isize>) -> Result<()>
     for job in JOBS.iter() {
         let start = Instant::now();
         loop {
-            if start.elapsed().as_secs() > 2 {
-                return Err(anyhow::anyhow!("Timed out"));
-            }
+            anyhow::ensure!(start.elapsed().as_secs() <= 2, "Timed out");
             match (*job)(app_dir) {
                 Ok(_) => {
                     unsafe { PostMessageW(hwnd, WM_JOB_UPDATED, WPARAM(0), LPARAM(0))? };