CAM: Multipass in Profile Op ignore start point

### Problem description

When using the "Number of passes" in Profile op, if you use the Start Point, it's ignored. This is a issue if your using the Start Point to control where a leadin/out happens.

Also, the offset in the task panel could be updated to support formulas so I can do 1/16 or something.

### Workbench affected?

CAM

### Steps to reproduce

Do a profile operation on a part, set the start point to the middle of the part. Toggle "Number of passes" to 2, and set a offset. You'll see the start point is no longer used.

### Expected behavior

Should use the start point

### Actual behavior

It doesn't use the start point.

### Development version About Info (in Safe Mode)

```shell
v1.1-rc3 self build.
```

### Last known good version (optional)

```shell
v1.0.2 ( I don't think we had use multiple passes)
```

Reproduce the issue in the CAM Profile operation by setting a middle Start Point, enabling Number of passes, and applying an offset. Inspect the Profile operation and its task panel, then verify that multiple passes preserve the selected start point; the offset formula request is a separate expected improvement.

Written by the indexing model from the issue text.