Update currentSearchMode from inside Search component

[MitchellMarkGeorge]

In the content script, there is a reference to the currentSearchMode that can be read from the background script. As part of #46 and #36, the user will be able to independently change the search mode, but this change won't be reflected in the content.ts file. To fix this, a function updateSearchMode() should be passed in as a prop and when the currentSearchMode in the Search component changes, it should call this function and update the currentSearchMode variable in the content.ts file.

This requires #46 to be merged.