Add plugin activity log file functionality

[parth-07]

This commit adds primitive support for plugin activity log file functionality.
It adds the option '--plugin-activity-log ' to the linker. With this option,
the linker emits a JSON plugin activity log file that contains the
ordered records of relevent plugin actions for later analysis and debugging. Currently,
only the following operations are fully supported: RemoveSymbol, UpdateChunks,
and updateLinkStat. The support for remaining operations will be added
in follow-up patches.

One key difference between the plugin operation information in the map-file
and the plugin activity log file is that in the map-file, the plugin
operations are separated as per operation type and the plugin. On the
other hand, in the plugin activity log file, we have a single array of
the operations by all the plugins. This allows to determine the total
ordering of the operations that can be important for various analysis.

[quic-seaswara]

This is going in the right direction.

It would be useful to combine just not the activity of adding and removing chunks, we might need linker state records and also the various operations it tries to invoke via the LinkerWrapper.

Can we also generate one file per plugin ?

[parth-07]

It would be useful to combine just not the activity of adding and removing chunks, we might need linker state records and also the various operations it tries to invoke via the LinkerWrapper.

Yes, totally agreed. This PR only adds the primitive framework for recording and printing the JSON file. Follow-up patches will extend the support for more relevant plugin operations.

Can we also generate one file per plugin ?

I do not think we should generate plugin actions per plugin as we plan to add a utility tool that users can use to filter plugin activities of a particular plugin. Please let me know your thoughts on this.

[quic-seaswara]

As usual, pls document :)

A script to read the JSON log file will be useful.

[parth-07]

As usual, pls document :)

Can we please document this once the functionality is close to complete? This PR only adds primitive support of this feature.