This is the IDE model from the https://data.services.jetbrains.com/products? feed.
Only `release` and `eap` IDEs will be supported for now.

This commit is in preparation for supporting placeholders like `last_release` or `last_eap`
in the URI handler. Unfortunately Toolbox does not expose a way to determine if a build like
251.2829.367 is an eap build or an actual release, so we have to look up the metadata in the
feed mentioned earlier.

from https://data.services.jetbrains.com/products?type=eap and https://data.services.jetbrains.com/products?&type=release

This commit implements an IDE feed manager that depending on whether Toolbox runs in offline mode or
not loads the eap and release information from two local json files or from the https://data.services.jetbrains.com/products.
The feed manager is also able to intersect a list of available build versions (the IDE versions available for install
on a workspace) with the list of versions fetched from the feed and return the latest version available for install.
The intersection happens only after the feed was filtered by product code release type.

Support for offline mode is WIP. The commit assumes that in offline mode Toolbox exposes a certain system property.

To be used later for resolving the placeholders.

…d` placeholders

This PR adds support for the IDE placeholders in the URI build number parameter. This is a request
coming from Netflix, the placeholders provide an easier way to fill in the build number from the
web dashboard without having to know the available versions of IDE from Toolbox.

IDE launch flow is refactored to support dynamic build selectors, and it also improves the
install/launch logic. When latest_eap or latest_release is used:
- prefer the newest matching version that is available for install
- install it only if it isn’t already installed
- fall back to the latest available version if no match exists
- show an error if none of the above happens

When latest_installed is used:
- launch the newest installed version
- if none are installed, install and launch the latest available version
- show an error if none of the above happens