Add command-line logging configuration

[RAOF]

Checklist

• Tests added and pass
• Adequate documentation added
• (optional) Added Screenshots or videos

[Copilot]

Pull request overview

This PR introduces tag-based log filtering that can be configured from the command line via a new --log-level option, integrating with Mir’s existing logging/tagging system and exposing the new functionality through the mircore ABI.

Changes:

• Add a new mir::logging::Tag subsystem with severity thresholds, tag enumeration, and severity parsing.
• Wire --log-level=tag=severity into the default server configuration so tags can be filtered at startup.
• Update unit/acceptance tests and documentation to cover the new command-line behavior.

Reviewed changes

Copilot reviewed 12 out of 13 changed files in this pull request and generated 9 comments.

Show a summary per file

File	Description
tests/unit-tests/logging/test_logging.cpp	Updates logging unit tests to account for tag severity filtering.
tests/unit-tests/CMakeLists.txt	Adjusts unit-test include paths.
tests/acceptance-tests/test_command_line_handling.cpp	Adds acceptance coverage for --log-level parsing and behavior.
src/platform/options/default_configuration.cpp	Implements the --log-level option and applies tag filters during option parsing.
src/platform/options/CMakeLists.txt	Updates include directories for the options object library.
src/core/symbols.map	Exports newly added logging/tag-related symbols (and formatter) in the mircore ABI map.
src/core/logging/tag.cpp	Introduces the new tag registry, severity parsing, and tag filtering logic.
src/core/logging/logger.cpp	Applies tag severity filtering when logging via tag lists.
src/core/CMakeLists.txt	Adds the new tag implementation and header to the mircore build.
include/core/mir/logging/tag.h	Adds the public tag/severity/filtering API and formatter declaration.
include/core/mir/logging/logger.h	Refactors to include tag definitions from the new header.
doc/sphinx/configuring/reference/options.md.include	Documents the new log-level option and tag list.
debian/libmircore2.symbols	Updates Debian symbols to reflect newly exported ABI.

Comments suppressed due to low confidence (1)

src/core/logging/tag.cpp:144

• lookup_tag() matches tags only by tag.name (leaf name), but list_known_tags() returns full hierarchical paths (e.g. core/input). As a result, tags shown to users (and potentially passed from configuration/CLI) won't be found.

Consider storing/looking up tags by their full path (or accepting both full path and leaf name) to keep list_known_tags() and set_severity() consistent and avoid name collisions.

auto lookup_tag(decltype(known_tags)::Locked const& tag_list, std::string_view tag_name) -> ml::Tag&
{
    for (auto& tag : *tag_list)
    {
        if (tag.name == tag_name)
        {
            return tag;
        }
    }
    BOOST_THROW_EXCEPTION((std::out_of_range{std::format("Looking up nonexistent tag: {}", tag_name)}));
}