Search LCSC based on existing BOM part numbers

[brendanm250]

• If I have already selected part numbers for components in my project and have them defined using manufacturer part numbers, the plugin doesn't seem to have any way to "see" those fields which means you have to manually copy paste part numbers.

• Add new columns for Manufacturer and (actual) Part Number which can be mapped/replaced to existing project fields (this also has the benefit of making it easier to