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/project/src/debugger/dap_store.rs

@@ -237,9 +237,7 @@ impl DapStore {
                     let binary = DebugAdapterBinary::from_proto(response)?;
                     let mut ssh_command = ssh_client.update(cx, |ssh, _| {
                         anyhow::Ok(SshCommand {
-                            arguments: ssh
-                                .ssh_args()
-                                .ok_or_else(|| anyhow!("SSH arguments not found"))?,
+                            arguments: ssh.ssh_args().context("SSH arguments not found")?,
                         })
                     })??;
 
@@ -316,10 +314,10 @@ impl DapStore {
                             return Ok(result);
                         }
 
-                        Err(anyhow!(
+                        anyhow::bail!(
                             "None of the locators for task `{}` completed successfully",
                             build_command.label
-                        ))
+                        )
                     })
                 } else {
                     Task::ready(Err(anyhow!(
@@ -735,7 +733,7 @@ impl DapStore {
         let task = envelope
             .payload
             .build_command
-            .ok_or_else(|| anyhow!("missing definition"))?;
+            .context("missing definition")?;
         let build_task = SpawnInTerminal::from_proto(task);
         let locator = envelope.payload.locator;
         let request = this
@@ -753,10 +751,7 @@ impl DapStore {
         mut cx: AsyncApp,
     ) -> Result<proto::DebugAdapterBinary> {
         let definition = DebugTaskDefinition::from_proto(
-            envelope
-                .payload
-                .definition
-                .ok_or_else(|| anyhow!("missing definition"))?,
+            envelope.payload.definition.context("missing definition")?,
         )?;
         let (tx, mut rx) = mpsc::unbounded();
         let session_id = envelope.payload.session_id;