* move bson-dsl.h to src/common

bson-dsl.h is not installed, but shared between libmongoc and libbson.
Intended to resolve CDRIVER-4673.

* do not define `mongo::detail::c_platform` if using system libbson

* add regression test

* fix more includes

* add include of common-prelude.h

* fix more include paths

This reverts commit 5774fe7b.

This is a result of Debian bug #1050439 being fixed.

Also, CDRIVER-4704

* Delete unused CMake module for legacy packaging
* Use qualified paths for libbson #includes
* Add an additional indirection for common name mangling
* More compact config checks
* Lift common platform requirements to top-level config checks
* Define options to toggle build/install of dynamic/shared
* Add a mongo_target_requirements() convenience function
* Conditional build of libbson static/shared
* Install shared/static separately:

Each type can be disabled individually, and even packaged individually.
Installs two export sets that are lazily included based on their presence
at import-time.

* Remove usage of CMake export()

It is unlikely that this was used by any users, as we did not provide any
mechanism to import these, and the feature itself is somewhat obscure. It
complicated certain build arrangements due to its interactions with
BUILD_INTERFACE. It can be restored in the future if necessary.

* Dedup link options from pkg-config generation

Nongenuine hosts are detected after SRV resolution; however, we cannot easily mock SRV responses so that is intentionally not tested.

Matching is anchored to the end of the host string. This necessitated moving mongoc-uri's ends_with function to mongoc-util in order to share it with mongoc-topology.

Co-authored-by: Ezra Chung <88335979+eramongodb@users.noreply.github.com>

* Refactor of the legacy cmake-package generation.

- Remove a lot of variable capture that was relied upon when generating
- The _LIBRARY/_LIBRARIES variables in the legacy packages now point to
  the imported target of their respective packages, which will handle
  all other "magic variable" definitions.

Co-authored-by: Kevin Albertson <kevin.albertson@10gen.com>

* Cleaner argument handling and type-checking in calc_release_version
* Speedup of calc_release_version by minimizing subprocesses

Instead of continually asking Git whether a particular commit hash is
pointed-to by a given tag, ask Git upfront for a mapping between all
commit hashes and the associated tags. Then, look for the commit in
the mapping as a single step.

* Cleanup and relocate BUILD_VERSION calculation
- The computation of BUILD_VERSION is now lifted above project(), which allows
  us to use that value in the project() call itself, giving us correct
  PROJECT_VERSION values throughout.
- Define BUILD_VERSION using mongo_setting(), and use the
  calc_release_version.py to compute its default value.

* Don't set a BUILD_VERSION cache var

* New CMake-based uninstall generation
* Fix: Don't use genex in places where old CMake can't use it

Co-authored-by: Roberto C. Sánchez <roberto@connexer.com>

* Update Poetry and requests
* Hold back PyYAML to avoid Cython errors

This fixes an issue on newer Python installs that don't have distutils handy, as well as address a dependabot PR that could not merge correctly (#1284). Also, hold back PyYAML to avoid Cython-related issues (fixed in PyYAML 6, but Shrub requires PyYAML 5)

* New documentation with new theming
* Prettier structure and output:
- Use subdirectories for organization.
- Import sphinx-design, which gives us useful components for richer HTML output.

* Migrate most of the installation docs away:
- New install docs and "supported platforms" have been refactored and
  replaced.
- The old "installing" page has been detached from the ToC and is now
  a placeholder referencing the new documentation pages. This will allow
  existing links in the wild to continue to work, while making the page
  itself invisible in the ToC tree.
* Create a howto on selecting an installation location
* Clean up and clarify platform support
* No dep on sphinxcontrib-moderncmakedomain:

Add a very minimal Sphinx extension sufficient to resolve references to
the CMake Sphinx object inventory. We don't need any more features for
now.

* Fix up package builds to install sphinx-design deps
* Vendor external inventories semi-automatically.

To support fully-offline builds of the documentation, vendor external
documentation inventories for intersphinx. These can be updated by
passing '-D update_external_inventories=1' to the sphinx-build command