Adding HalstackProvider documentation

[jsuarezgonz]

Checklist
(Check off all the items before submitting)

• Build process is done without errors and all tests pass in /lib directory.
• Self-reviewed the code prior to submitting.
• Meets accessibility standards.
• Added/updated documentation to /website as needed.
• Added/updated tests as needed.

Description

• A new 'Utilities' section is created with the HalstackProvider documentation. This documentation includes examples of how to use the HalstackProvider with the opinionated theme, the advanced theme, and an example of label translation.

• Themes documentation is modified to explain in a more detailed way the different theming strategies we have.

[GomezIvann]

The extension of the example files is not correct since we are not using actual JSX code inside of them. For example, advancedTheme.tsx should be instead advancedTheme.ts

[GomezIvann]

These files are missing from changing their extension (correct me if I'm wrong but any of them has JSX code):

• bloomTheme.tsx
• customTranslations.tsx
• defaultAdvancedTheme.tsx
• opinionatedTheme.tsx