Add support for lock files

[psmulovics]

Add option to add the needed settings for lock files:

• add RestorePackagesWithLockFile with true if missing from csproj
• try to add --locked-mode to dotnet restore commands

[BalassaMarton]

I'm a bit skeptical about this command.

add RestorePackagesWithLockFile with true if missing from csproj

Copy-pasting this property from the first hit on google is faster than executing a command, isn't it?

try to add --locked-mode to dotnet restore commands

Add to what?