Fixes #1852

Info

Clap's parsing for variable-length argument lists has precedence rules for what happens when a potential vararg overlaps with a known flag value (see https://docs.rs/clap/latest/clap/struct.Arg.html#method.allow_hyphen_values):

1. If we are already in a list of variable args, the args take precedence and any potential flags are ignored (flags are treated as part of the vararg)
2. If we are not already in a list of variable args, then known flags take precedence and are parsed as such, rather than starting the vararg list

As a result of this precedence, with volta run set up to have args be separate from command, we could run into parsing issues with commands that have flags that overlap with Volta's. For example:

volta run node -h

When parsing this, Clap would see node as the command, and then it would parse -h as Volta's -h (help) flag and print Volta's help. This is because the variable-length args hadn't started yet (we hadn't run into any unknown positional arguments), so Clap treated -h as a known flag with higher precedence. This is exactly the opposite of what we actually want for volta run

Instead, what we want is that everything after the command argument should be treated as part of the arguments to the command; regardless of whether the flag overlaps with Volta's flags.

To achieve that, we combine command and args into a single vararg, so that by virtue of having a command in the first place, the vararg has started parsing and Clap will treat any flags as more argument values, rather than as flags.

Changes

• Updated the command definition of Run to have command_and_args as a single list instead of a value and a list.
• Pulled the command and args out inside of Command::run so that they can still be passed to execute_tool in the same manner as before

Tested

• Ran volta run node -h and verified that it correctly runs node -h, rather than showing the help output for volta run
• Ran volta run node to make sure the arg processing is handled correctly when there are no additional arguments.
• Ran volta run to validate that Clap shows a "missing required argument" message rather than creating a Run instance with an empty command_and_args vector.

Note

• AFAICT, this parsing idiosyncrasy has existed since we implemented volta run, however it is a higher priority now because we switched the 3rd-party shims on Windows to use volta run internally in Replace Windows symlinks with volta run scripts #1755