Make Custom Enums Packed

[Koloss0]

Enums in C are forced to be ints. However, the custom ID types in can_command_list.h such as PowerLineID are meant to be a single byte in width. To rectify this, custom ID types should be typedef'd to uint8_t. The enum keys can become #defines instead.

[Koloss0]

Update: an alternative fix is to make the enums packed with GCC attributes. E.g:

typedef enum __attribute__((packed)) {
    ZERO = 0,
    ONE,
} MyPackedEnum;