Fix Insiders versioning with Prisma 3.x

[janpio]

Prisma Insiders versioning will start with 1.0.x again (for 3.1.0-dev.x) - which we already used in the past (for 2.1.0-dev.x). This will lead to clashes and also probably lead to new versions not being installed as they are lower than old versions.

(This is caused by the VSCode marketplace tooling limitation around version numbers, that do not allow using of suffices like -dev.x in version numbers, making us choose this weird versioning scheme to work around it)

[Jolg42]

I think it would make sense to try to have only one insider versioning like

// Add Prisma major in insider major to make it compatible with major bumps
// Example for Prisma 2.30.0
// 231.0.1
// Example for Prisma 3.1.0
// 301.0.1
...

[janpio]

Did not actually become a problem yet because of: https://github.com/prisma/language-tools/issues/867