Transaction Store and Load API

[kontura]

Operations such as System Upgrade, Offline Upgrade, History Replay, History Redo, History Store and others require an API for storing and loading transactions.

• Add an API to store (serialize) a transaction into a JSON data format. We will need to be able to serialize both base::transaction and transaction::transaction (history transaction).
• Add API to load the JSON serialized transaction into a Goal.

The first part is done but we still need:

• Fix environments handling - requires ABI break
• Add groups/environments replaying without loaded repos
• Verify functionality without loading repos
• Enable/Add CI tests
• Integrate running without loading repos into offline command (system-upgrade)

The API should support packages (RPMs), groups, environments and potentially also modules.

[kontura]

The first draft of the API is in PR: #978

[evan-goode]

Second draft of the API is PR #1005

[jan-kolarik]

Related issue to the mentioned ABI break: #1025.

[kontura]

Comps and running without loading repos PR: #1264

[jan-kolarik]

Make sure these scenarios are covered:

• Unexpected results in 'dnf history rollback' dnf#2031
• https://issues.redhat.com/browse/RHEL-17494

Related PR in libdnf:

• MergedTransaction: Calculate RPM difference between two same versions as no-op libdnf#1644.

[kontura]

The API is finished.