Speed up get_packages_for_component_id and prepare for future improvements

[leolost2605]

Ok this is a wall of text for really not that many lines of code that were changed but it goes a bit in depth about improvements and some future plans I have :)

Includes #2419

Introduce a component class that holds all packages that belong to a component. Then introduce a hashmap that maps component ids to the new component class.
Because the component class also implements listmodel we can flatten it to the packages instead of having a separate package store. This has the advantage that we can in the future much more easily obtain a package list with only unique packages by just mapping the components to the package with the highest origin score instead of flattening it to all packages. This can be done only a single time in the backend and allow all calls to profit from this. In the future this will speed up and allow to use listmodels for get_packages_for_author, get_packages_for_category, creating the search, etc.

Right now we also get a major performance gain through the second commit (Speedup get_packages_for_component_id).
This call goes from O(n) to O(1) with n being the number of all packages (>10000 with flathub).
The call happens quite often because we need it to determine the origin packages for a given package which happens e.g. everytime a InstalledPackageRow is constructed (i.e. at startup for every installed package) and every time an appinfoview is opened.
This means that with this PR the startup time is a bit faster (which is ofc not that impactful because most of the time is used for loading the packages but apart from that it reduces time by I would say 70-80% see the attached flamegraphs). But it also improves the time needed to construct an appinfoview which makes browsing a lot smoother IMO because we now always get the smooth animation and it doesn't lag because we take too long to get the packages (at least it felt smoother to me 🤷).

A bit background: I found this through some rough profiling:

On main, zoomed to application.activate :

With this PR once again zoomed to application.activate (it isn't big enough to be really visible):

[leolost2605]

Ok should be ready again. I wanted to improve how we add components to the component store a bit and then added some comments because we have to be a bit careful about what we can do on a worker thread and what not and in what order we do things.