feat(parsers): add HTML parser combine it with telegram message entities

[uwinx]

Description

This PR introduces plain HTML text -> telegram text entity objects converter.

Rationale

This is required to deal with text partitioning by the length.
imaginary API:

from aiogram.utils.markdown import into_parts

for raw, fmt in into_parts("<b>B</b><strong>S</strong>", maxlen=1, maxentities=1):
    await bot.send_message(raw, entities=fmt)

Type of change

• New feature (non-breaking change which adds functionality)

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes

[uwinx]

@JrooTJunior, we can add this now and see what feedback do we get. depending on that I can implement smartish text splitting.

[evgfilim1]

Don't you want to add tests for this? It would be very nice

[uwinx]

@JrooTJunior, still need this?