feat(vscode): Add syntax highlighting to `Prisma.sql`

[ajmnz]

Fixes #1533, adds syntax highlighting to the Prisma.sql helper.

As I understand, only $queryRaw and $executeRaw have syntax highlighting because they are considered "safe". Docs do not make references to Prisma.sql being unsafe.

[CLAassistant]

All committers have signed the CLA.

[andreasvh-conceto]

Hi, this is such a useful feature. In our projects we use queryRaw, but would prefer to create an Prisma.sql , to pass this query object around. But without highlighting this is just meh....

@ajmnz @janpio any idea or possibility, to merge this? :)

[andreasvh-conceto]

This will fix https://github.com/prisma/language-tools/issues/1533