Make Link.to and Button.to more strict

Signed-off-by: Fredrik Adelöw <freben@gmail.com>

.changeset/tasty-falcons-press.md

@@ -0,0 +1,5 @@
+---
+'@backstage/core-components': minor
+---
+
+Made the `to` prop of `Button` and `Link` more strict, only supporting plain strings. It used to be the case that this prop was unexpectedly too liberal, making it look like we supported the complex `react-router-dom` object form of the parameter as well, which led to unexpected results at runtime.

packages/core-components/api-report.md

@@ -613,8 +613,9 @@ export const Link: (props: LinkProps) => JSX.Element;
 // Warning: (ae-missing-release-tag) "LinkProps" is exported by the package, but it is missing a release tag (@alpha, @beta, @public, or @internal)
 //
 // @public (undocumented)
-export type LinkProps = LinkProps_2 &
-  LinkProps_3 & {
+export type LinkProps = Omit<LinkProps_2, 'to'> &
+  Omit<LinkProps_3, 'to'> & {
+    to: string;
     component?: ElementType<any>;
     noTrack?: boolean;
   };

packages/core-components/src/components/Link/Link.tsx

@@ -47,8 +47,9 @@ const useStyles = makeStyles(
 
 export const isExternalUri = (uri: string) => /^([a-z+.-]+):/.test(uri);
 
-export type LinkProps = MaterialLinkProps &
-  RouterLinkProps & {
+export type LinkProps = Omit<MaterialLinkProps, 'to'> &
+  Omit<RouterLinkProps, 'to'> & {
+    to: string;
     component?: ElementType<any>;
     noTrack?: boolean;
   };