Fix delay in message context menu buttons added by FlowCrypt

[martgil]

Description:

The context menu entries added by the FlowCrypt browser extension in Gmail does have a few second/miliseconds delay before getting added for the first time.

Users may accidentally click the secure message actions by FlowCrypt when they delay occurs instead of the regular reply button - not very user friendly there. Let's find a solution to fix the delay so that added buttons in the context menu be present there upon user clicks the context menu button.

Steps to reproduce:

1. Open any FlowCrypt extension recognizable email.
2. Click on the context menu button on the right side corner of the email thread.
3. Observe the context menu and the addition of FlowCrypt Secure action buttons with slight delay before getting injected into the menu.

Reference: https://mail.google.com/mail/u/human@flowcrypt.com/#inbox/FMfcgzQZSjbvlFqBsVKKzJtBQMwWFlbh

[martgil]

Make sure to inform the reporting user after this GH issue closed as completed.