Skip field when `bcl` tag is equal to `"-"`

Hello,

As the title says, it would be great it the parser would skip the block if the struct has `bcl:"-"`:
```go
type logging struct {
	Level     string     `bcl:"level"`
	SlogLevel slog.Level `bcl:"-"`
	Format    string     `bcl:"format"`
}
```

---
- Also could it possible to add an ulterior check for the primitive type of an enum, this way special fields like `slog.Level` could be parsed?