generatePath was doing multiple passes on the `path` using string replace, the first two passes were applying parameters, the third pass was doing a cleanup and the fourth path was applying the `splat`.
It was possible to get incorrect results while applying `splat` when the last parameter value ended with `*`:

```ts
const path = generatePath("/route/:name", {
    name: encodeURIComponent("includes *asterisk at the end*"),
})
```
```
    Expected: "/route/includes *asterisk at the end*"
    Received: "/route/includes *asterisk at the end"
```
results of the first two passes return the value of `/route/*asterisk at the end*` which was later treated as path with the splat resulting in the last asterisk removed.

it was also possible to inject the splat value unintentionally
```ts
generatePath("/courses/:name", { name: "foo*", "*": "splat_should_not_be_added" })
```
```
    Expected: "/courses/foo*"
    Received: "/courses/foosplat_should_not_be_added"
```

A safer option, instead of mutating a global path multiple times, is to split the path into segments, process each segment in isolation and then join them back together.

fixes remix-run#9051

paramName for the splat wasn't correctly resolved when the pas is `/*`