Update net-im/libqmatrixclient and net-im/quaternion in tandem.

New release of libqmatrixclient (which breaks API compatibility) and
a beta for quaternion (its only client).

https://github.com/QMatrixClient/libqmatrixclient/releases/tag/0.5.0
https://github.com/QMatrixClient/Quaternion/releases/tag/0.0.9.4-beta1

Summarized:

• (packaging) QtMultimedia (video support) and QtKeychain (for secure storage) are now added as dependencies.
• (user-visible) Many UI improvements.

This could use some work on the BUILD_DEPENDS to make sure that quaternion
is upgraded together with the static library it depends on.