Refresh documentation styling with Furo theme

[vlad-perevezentsev]

This PR proposes a refresh of dpnp documentation styling and layout by migrating to the furo theme and improving the overall API documentation appearance

• Replace sphinx_rtd_theme with furo
• Update documentation dependencies in pyproject.toml, building_docs.yml and base_build_docs.txt
• Redesign the landing page using sphinx-design cards
• Add custom CSS/JS for cleaner NumPy-style API formatting
• Improve tables, section headers, parameter formatting and function signatures

dpnp logo (dpnp.svg) will be added in the future

• Have you provided a meaningful PR description?
• Have you added a test, reproducer or referred to an issue with a reproducer?
• Have you tested your changes locally for CPU and GPU devices?
• Have you made sure that new changes do not introduce compiler warnings?
• Have you checked performance impact of proposed changes?
• Have you added documentation for your changes, if necessary?
• Have you added your changes to the changelog?

[github-actions]

View rendered docs @ https://intelpython.github.io/dpnp/pull/2934/index.html

[coveralls]

coverage: 78.251%. remained the same — update_dpnp_docs into master

[github-actions]

Array API standard conformance tests for dpnp=0.21.0dev0=py313h509198e_82 ran successfully.
Passed: 1356
Failed: 4
Skipped: 16

[antonwolfy]

The tab with rendered documentation is currently named as: dpnpData Parallel ... - without any space or separator.
It might be better to do as dpctl: Data Parallel Control (dpctl)

[antonwolfy]

Also it has too long dpnp version:

but we only need 0.21.0dev0

[antonwolfy]

Would it be better to rephrase something like:
DPNP is a NumPy-compatible array library that can be executed on any data parallel device. DPNP acts as a drop-in replacement of core NumPy functions and numerical data types.

I wonder about using the word subset of NumPy because it doesn't bring why the user need to use DPNP and what is the subset means in terms of number of numpy functions.

[antonwolfy]

Also we started to add implementation for some SciPy-relating function and so probably need to highlight that as well.

[antonwolfy]

Do we need to place a link to dpctl documentaion?

[antonwolfy]

Do we need to have that on the main page as well with some description?
It currently provides overview for the function from the extensions.