Add a cargo frc init project generator

[Lytigas]

Could also add something like cargo frc configure that will search for an FRC compiler and install it for you.

[grebneerg]

I'd like to take a stab at implementing this.

[grebneerg]

For cargo frc configure, we will either need to either need to edit the user's global cargo config file when we install or somehow store the install location to place in individual project cargo configs. The second option sounds more user friendly to me, but increases complexity significantly. Anyone have any thoughts on this?

Additionally, do we want to do anything to support multiple toolchain versions?

[auscompgeek]

We should install the FRC toolchain in the standard place (~/wpilib/$YEAR) and point project cargo configs to whatever arm-frc$YEAR-linux-gnueabi-gcc we can find, if you ask me.

[auscompgeek]

Although… I feel the alternative of #87 would be better. Then we don't break if .cargo/config is checked into git, and it opens up the possibility of running simulation too.