fix: capture complete extension load time

[peternhale]

• Add utility function to vscode-utils that returns the activation event for a given extension from extension host log
• At the beginning of each extension’s activate function -- Capture the timestamp of function entry -- Capture the timestamp of the extension activation event using util from vscode-utils
• Send activation telemetry record with -- Time spent in activation function (this is the current data) -- Timestamp of activate function entry -- Timestamp of extension activation -- Time spent for activation (activate function exit timestamp - extension activation event timestamp) in milliseconds

AC:

• vscode-utils provides a function that returns the ext host extension activation timestamp for the provided extension id
• sendActivation telemetry method will accept -- Time spent in activation function (this is the current data) -- Timestamp of activate function entry -- Timestamp of extension activation -- Time spent for activation (activate function exit timestamp - extension activation event timestamp) in milliseconds
• One should be able to visit AppInsights to verify the new data are available in the activation telemetry record

@W-14915912@

[CristiCanizales]

QE notes: Confirmed the data is being sent to AppInsights ✅