Go: Implement LastSave command

[EdricCua]

Issue link

This Pull Request is linked to issue (URL): #3399

Checklist

Before submitting the PR make sure the following are checked:

• This Pull Request is related to one issue.
• Commit message has a detailed description of what changed and why.
• Tests are added or updated.
• CHANGELOG.md and documentation files are updated.
• Destination branch is correct - main or release
• Create merge commit if merging release branch into main, squash otherwise.

[Yury-Fridlyand]

What about lastsave for standalone client?

[Yury-Fridlyand]

1. Need to move examples to the corresponding file(s).
2. Need to add a changelog entry as of now.
3. RouteOption was reworked in 1.3 branch.

Please wait for backporting all changes from release-1.3 branch. You can merge/rebase you branch after that and implement required fixes.
UPD backported in #3202

[Yury-Fridlyand]

Please add changelog and fix PR description (needs a link to an issue)

[Yury-Fridlyand]

Please add a changelog entry and update PR description by adding a correct issue link.
Fix CI failures.