Fix link resolving in scaladoc and fix invalid links in docs (scala#18465)

This PR combines scala#17099 changes with previous link resolver, which fixes
scala#18285, scala#18444 and brings down `Unable to resolve link` warnings from 81
to 7.
4 more links are fixed manually in `.md` files, which leaves us with 3
warnings.
Those 3 are references to source code inside `scaladoc.md`:

https://github.com/lampepfl/dotty/blob/45f633d0667c702fa75efcfda91b434bb72f04dc/docs/_docs/contributing/scaladoc.md?plain=1#L77-L87
Those won't work online anyway (unless we link to github), so we might
want change them.

Author: nicolasstucki

docs/_docs/contributing/architecture/types.md

@@ -11,7 +11,7 @@ format corresponding to the backing data structure, e.g. `ExprType(...)`
 corresponds to `class ExprType`, defined in [Types.scala].
 
 > You can inspect the representation of any type using the [dotty.tools.printTypes][DottyTypeStealer]
-> script, its usage and integration into your debugging workflow is [described here](../issues/inspection.md).
+> script, its usage and integration into your debugging workflow is [described here](../debugging/inspection.md).
 
 ### Types of Definitions
 

docs/_docs/contributing/debugging/debugging.md

@@ -9,6 +9,6 @@ that you're having issues with. This can be just inspecting the trees of your
 code or stepping through the dotty codebase with a Debugger.
 
 The following sections will help you with this:
-- [Debugging with your IDE](./ide-debugging.md.md)
+- [Debugging with your IDE](./ide-debugging.md)
 - [How to Inspect Values](./inspection.md)
 - [Other Debugging Techniques](./other-debugging.md)

docs/_docs/contributing/issues/cause.md

@@ -69,7 +69,7 @@ This flag forces a stack trace to be printed each time an error happens, from th
 Analysing the trace will give you a clue about the objects involved in producing
 the error. For example, you can add some debug statements before the error is
 issued to discover the state of the compiler. [See some useful ways to debug
-values.](./debugging/inspection.md)
+values.](../debugging/inspection.md)
 
 ### Where was a particular object created?
 

docs/_docs/contributing/issues/reproduce.md

@@ -133,7 +133,7 @@ not be passed). This saves typing the same arguments each time you want to use t
 
 The following `launch.iss` file is an example of how you can use multiline
 commands as a template for solving issues that [run compiled
-code](../issues/testing.md#checking-program-output). It demonstrates configuring
+code](../testing.md#checking-program-output). It demonstrates configuring
 the `scala3/scalac` command using compiler flags, which are commented out. Put
 your favourite flags there for quick usage.
 

scaladoc/src/dotty/tools/scaladoc/renderers/SiteRenderer.scala

@@ -29,6 +29,14 @@ trait SiteRenderer(using DocContext) extends Locations:
 
   def siteContent(pageDri: DRI, content: ResolvedTemplate): PageContent =
     import content.ctx
+
+    def tryAsDriPlain(str: String): Option[String] =
+      val (path, prefix) = str match
+        case HashRegex(path, prefix) => (path, prefix)
+        case _ => (str, "")
+      val res = ctx.driForLink(content.template.file, path).filter(driExists)
+      res.headOption.map(pathToPage(pageDri, _) + prefix)
+
     def tryAsDri(str: String): Option[String] =
       val newStr =
         str.dropWhile(c => c == '.' || c == '/').replaceAll("/", ".") match
@@ -51,7 +59,7 @@ trait SiteRenderer(using DocContext) extends Locations:
       )(
         resolveLink(pageDri, str.stripPrefix("/"))
       )
-      def asStaticSite: Option[String] = tryAsDri(str)
+      def asStaticSite: Option[String] = tryAsDriPlain(str).orElse(tryAsDri(str))
 
       /* Link resolving checks performs multiple strategies with following priority:
         1. We check if the link is a valid URL e.g. http://dotty.epfl.ch