[feat] add update_in_insert and lazy_update_in_insert options

[spflaumer]

The update_in_insert and lazy_update_in_insert options, with their respective vim.b.update_in_insert and vim.b.lazy_update_in_insert counterparts, allow the user of the plugin to enable updating the context while in Insert mode.

Currently, the information returned by get_data, and it's get_location wrapper, is the same as when first entering Insert mode.
Now the context will update in insert mode, providing a fresh context with the "CursorHoldI" and "CursorMovedI" events.

[SmiteshP]

Does this achieve same as #168 ?

[spflaumer]

Yes, but this also adds options to control that behavior for users that may not want updates in Insert mode. Reading the code a year later, it isn't the best and the commit messages suck, so I might want to redo this if you consider the config options a useful addition

[SmiteshP]

Sure 👍🏽