feat(amazonq): re-add activeState/line trackers

[jpinkney-aws]

Problem

• "Amazon Q is generating ..." does not show with the lsp mode

Solution

• re-add the line tracker with tests
• re-implement the activeState tracker

Notes

In master the active state tracker decides whether or not to show "Amazon Q is generating ..." by the following:

• When a change is made, the auto trigger decides whether or not to start a recommendation request. When a recommendation requests eventually starts, an event is sent to the active state tracker to tell it to start showing the "Amazon Q is generating ..." message. When the first recommendation starts loading and the results are shown to the user another event is sent telling it to hide the message. It de-bounces this message showing every 1000ms so that the message is not constantly toggling on/off

In this implementation its slightly different:

• VSCode decides when to trigger the inline completion through their inline completion provider. From here we show the "Amazon Q is generating ... " message until the first recommendation is received from the language server and shown to the user. It still de-bounces this message every 1000ms so that users aren't shown it too often

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[github-actions]

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