feat: add user-level parameter autofill (#11731)

This PR solves #10478 by auto-filling previously used template values in create and update workspace flows.

I decided against explicit user values in settings for these reasons:

* Autofill is far easier to implement
* Users benefit from autofill _by default_ — we don't need to teach them new concepts
* If we decide that autofill creates more harm than good, we can remove it without breaking compatibility

codersdk/users.go

@@ -221,6 +221,27 @@ type OIDCAuthMethod struct {
 	IconURL    string `json:"iconUrl"`
 }
 
+type UserParameter struct {
+	Name  string `json:"name"`
+	Value string `json:"value"`
+}
+
+// UserAutofillParameters returns all recently used parameters for the given user.
+func (c *Client) UserAutofillParameters(ctx context.Context, user string, templateID uuid.UUID) ([]UserParameter, error) {
+	res, err := c.Request(ctx, http.MethodGet, fmt.Sprintf("/api/v2/users/%s/autofill-parameters?template_id=%s", user, templateID), nil)
+	if err != nil {
+		return nil, err
+	}
+	defer res.Body.Close()
+
+	if res.StatusCode != http.StatusOK {
+		return nil, ReadBodyAsError(res)
+	}
+
+	var params []UserParameter
+	return params, json.NewDecoder(res.Body).Decode(&params)
+}
+
 // HasFirstUser returns whether the first user has been created.
 func (c *Client) HasFirstUser(ctx context.Context) (bool, error) {
 	res, err := c.Request(ctx, http.MethodGet, "/api/v2/users/first", nil)