VSCode marketplace improvements

[certik]

• Call it LFortran, not lfortran-lsp
• Add the LFortran logo
• Add some nice image or video how it looks

[dylon]

These have been resolved in the latest commit to main, but I will wait for our next deployment to conda-forge before closing the ticket. I will have to wait until then to re-publish the extension to the Marketplace as LFortran.