Add UTF-8 and byte strings

[pavel-kirienko]

Closes #51

See OpenCyphal/pydsdl#97

[Copilot]

Pull Request Overview

This PR introduces support for UTF-8 strings and byte strings in the DSDL specification by updating documentation and grammar rules. Key changes include:

• Adding a bullet point in the introduction outlining support for UTF-8 strings and byte strings.
• Adding new descriptive entries for UTF-8 octet and byte types in the serializable types documentation.
• Updating reserved identifier lists and grammar rules to accommodate the new primitive types.

Reviewed Changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 1 comment.

File	Description
specification/introduction/introduction.tex	Added note about support for UTF-8 and byte strings.
specification/dsdl/serializable_types.tex	Added detailed entries for UTF-8 octet and byte types with minor typo.
specification/dsdl/grammar.tex	Updated reserved identifiers to include new primitive types.
specification/dsdl/grammar.parsimonious	Modified grammar rules to accommodate the new primitive types.

[thirtytwobits]

I approve but I think the copilot suggestion is correct, that there's a misspelling?