feat: add CLI support for user secrets (#24270)

Adds a coder secret command group for managing user secrets from the
CLI, with create, update, list, and delete subcommands backed by the
existing user secret API.

This branch adds CLI test coverage and refreshes the generated help
output and CLI reference docs for the new command group.

docs/reference/cli/secret_create.md

@@ -0,0 +1,50 @@
+<!-- DO NOT EDIT | GENERATED CONTENT -->
+# secret create
+
+Create a secret
+
+## Usage
+
+```console
+coder secret create [flags] <name>
+```
+
+## Description
+
+```console
+Provide the secret value with --value or non-interactive stdin (pipe or redirect).
+```
+
+## Options
+
+### --value
+
+|      |                     |
+|------|---------------------|
+| Type | <code>string</code> |
+
+Set the secret value. For security reasons, prefer non-interactive stdin (pipe or redirect).
+
+### --description
+
+|      |                     |
+|------|---------------------|
+| Type | <code>string</code> |
+
+Set the secret description.
+
+### --env
+
+|      |                     |
+|------|---------------------|
+| Type | <code>string</code> |
+
+Name of the workspace environment variable that this secret will set.
+
+### --file
+
+|      |                     |
+|------|---------------------|
+| Type | <code>string</code> |
+
+Workspace file path where this secret will be written. Must start with ~/ or /.