Process Raw Author Metadata safely

In typecript, we ensure that authors that arrive at the filter have been transformed into an array. When we call this directly with document YAML, the authors may be a simple string, like:

```
author: Harley Malloc
```

We need to deal with this case as well.

Author: dragonstyle

src/resources/filters/common/authors.lua

@@ -140,15 +140,25 @@ local kAffiliationAliasedFields = {
 -- a simple incremental counter that can be used for things like note numbers
 local kNumber = "number"
 
-function processAuthorMeta(meta, authorInput)
+function processAuthorMeta(meta)
   if not _quarto.format.isHtmlOutput() and not _quarto.format.isLatexOutput() and not _quarto.format.isIpynbOutput() and not _quarto.format.isDocxOutput() then
     return
   end
 
-  if authorInput == nil then
-    authorInput = kAuthorInput
+  -- prefer to render 'authors' if it is available
+  local authorsRaw = meta[kAuthor]
+  if meta[kAUthors] then 
+    authorsRaw = meta[kAuthors]
   end
-  local authorsRaw = meta[authorInput]
+
+  -- authors should be a table of tables (e.g. it should be an array of inlines or tables)
+  -- if it isn't, transform it into one
+  if type(authorsRaw) == "table" then
+    if (type(authorsRaw[1]) ~= "table") then
+      authorsRaw = {authorsRaw}
+    end
+  end
+ 
 
   -- the normalized authors
   local authors = {}

src/resources/filters/quarto-post/book.lua

@@ -19,11 +19,7 @@ function quartoBook()
         local template = el.attr.attributes['template']
 
         -- process any author information
-        local input = 'author'
-        if renderedDoc.meta['authors'] then
-          input = 'authors'
-        end
-        local processedMeta = processAuthorMeta(renderedDoc.meta, input)
+        local processedMeta = processAuthorMeta(renderedDoc.meta)
 
         -- read the title block template
         local renderedBlocks = compileTemplate(template, processedMeta)