Add notifiation handlers, make them testable, and fix them

[igrep]

Important commits:

• 2cc5a85 🆕 Handle 'notify_delete_acquaintance' notification
• c6f2819 Implement notify_add_talkers and notify_add_acquaintance
• 8e4ea84 Pass IDs directly to RPC functions.
• 6ed05ad Add user-defined notification handlers and fix addTalker / deleterTalker

[restyled-io[bot]]

Hey there-

I'm a bot, here to let you know that some code in this PR might not match the team's automated styling. I ran the team's auto-reformatting tools on the files changed in this PR and found some differences. Those differences can be seen in #90.

Please see that Pull Request's description for more details.

[restyled-io[bot]]

Hey there-

I'm a bot, here to let you know that some code in this PR might not match the team's automated styling. I ran the team's auto-reformatting tools on the files changed in this PR and found some differences. Those differences can be seen in #91.

Please see that Pull Request's description for more details.

[restyled-io[bot]]

Hey there-

I'm a bot, here to let you know that some code in this PR might not match the team's automated styling. I ran the team's auto-reformatting tools on the files changed in this PR and found some differences. Those differences can be seen in #92.

Please see that Pull Request's description for more details.

[restyled-io[bot]]

Hey there-

I'm a bot, here to let you know that some code in this PR might not match the team's automated styling. I ran the team's auto-reformatting tools on the files changed in this PR and found some differences. Those differences can be seen in #93.

Please see that Pull Request's description for more details.