[PageHeader] Allow multiple breadcrumbs that are not links

[null93]

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Simply allows multiple breadcrumbs to exist that are not links. An application of this would be having a top level breadcrumb that you would not want to be a link but instead be static text.

For example, given this definition for breadcrumbs:

[
    { title: "UOW" },
    { title: "Teams", path: "/teams" },
    { title: "New" },
]

Before, the last breadcrumb was always static text and all breadcrumbs before it were links.

After, the breadcrumb is a link if it has a truthy value for path and it is static text if that value of path is falsy.

[mui-bot]

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[Janpot]

Sorry, approved too fast. Let's use the same key everywhere. Also, can the path property be made optional now in the BreadCrumb type?

[Janpot]

Looks great, thank you!