Simplify erbb install usage

[ohmtech-rdi]

Currently, the erbb install command is not great:

• As soon as openocd is installed, it is used instead of dfu-util which might be unsetting, if the user doesn't have a stlink programmer,
• erbb install should probably use dfu-util by default,
• openocd is probably a bad command option, since it mentions the tooling rather than was system is used. Maybe jtag or stlink would be better
• erbb install bootloader would feel more natural than erbb bootloader

Additionally, the DFU util error is a bit misleading, so something should be done about that, to report success.