zed_extension_api: Bump to v0.1.0 (#16158)

This PR changes v0.0.7 of the extension API to v0.1.0.

We had a false-start in releasing v0.0.7, which has since been yanked,
so we need a new version number. We'll publish v0.1.0 to crates.io once
the Preview build is out tomorrow.

We're incrementing the minor version so that we have some leeway in
putting out patch releases of the crate within a given extension API
release.

Release Notes:

- N/A

crates/extension_api/wit/since_v0.1.0/slash-command.wit

@@ -0,0 +1,41 @@
+interface slash-command {
+    use common.{range};
+
+    /// A slash command for use in the Assistant.
+    record slash-command {
+        /// The name of the slash command.
+        name: string,
+        /// The description of the slash command.
+        description: string,
+        /// The tooltip text to display for the run button.
+        tooltip-text: string,
+        /// Whether this slash command requires an argument.
+        requires-argument: bool,
+    }
+
+    /// The output of a slash command.
+    record slash-command-output {
+        /// The text produced by the slash command.
+        text: string,
+        /// The list of sections to show in the slash command placeholder.
+        sections: list<slash-command-output-section>,
+    }
+
+    /// A section in the slash command output.
+    record slash-command-output-section {
+        /// The range this section occupies.
+        range: range,
+        /// The label to display in the placeholder for this section.
+        label: string,
+    }
+
+    /// A completion for a slash command argument.
+    record slash-command-argument-completion {
+        /// The label to display for this completion.
+        label: string,
+        /// The new text that should be inserted into the command when this completion is accepted.
+        new-text: string,
+        /// Whether the command should be run when accepting this completion.
+        run-command: bool,
+    }
+}