fix: prevent double loading spinners

[Aditya9985]

When using a recent version of this library and @formio/js, two loading spinners were displayed for a single form. This was caused by both libraries showing their loading indicators simultaneously.

This PR fixes the issue by:

1. Adding a default template configuration that sets a single loading indicator
2. Initializing the template on library import to ensure it's set before Form components render

The solution:

• Created a new templates.ts file that sets up the default template configuration
• The template is initialized when the library is imported, ensuring consistent loading indicator behavior
• Uses bootstrap3 framework for compatibility

To test:

1. Import the Form component from @formio/react
2. Create a form with a remote source like: <Form src="https://examples.form.io/example" />
3. Observe that only one loading spinner appears while the form loads

Fixes #590