SPDX license expression support

This project aims to support the detection and reporting of SPDX License Expressions. Currently, FOSSology uses regular expressions, full-text match, and fuzzy match to scan licenses, stores all types of license expressions as a list of licenses, and wrongly classifies them as conjunctive licenses or disjunctive licenses. It also stores license exceptions as licenses and does not differentiate exceptions from licenses. In the project, I will be working on scanning license expressions using regular expressions with Ojo, storing them in the database, creating UI components to see license expressions in the file clearing page, and finally updating reports to export the expressions in the correct format.