[Schematics CLI] Numeric strings in schematics options

### Command

generate

### Is this a regression?

- [ ] Yes, this behavior used to work in the previous version

### The previous version in which this bug was not present was

_No response_

### Description

From http://b/196605664.

Apparently you can't pass in a numeric value into a string argument in schematics. This appears to be interpreted as number and leads to a validation error.

### Minimal Reproduction

```
$ schematics run test --stringValue "1234"
Schematic input does not validate against the Schema: {"stringValue":1234}
Errors:

Data path ".stringValue" should be string.
```

Minimist seems to interpret "1234" as a number instead of a string, and schematics treats that as a type mismatch.

### Exception or Error

_No response_

### Your Environment

```text
See http://b/196605664.
```

### Anything else relevant?

_No response_

Start at the generate command's option parsing and the minimist handling described in the report, then reproduce the command with --stringValue "1234". Trace where the quoted value becomes a number and verify that numeric-looking values passed to string options reach schema validation as strings.

Written by the indexing model from the issue text.