feat(plugins): add toml support for frontmatter (#418)

* feat(plugins): add toml support for frontmatter

Currently frontmatter is expected to be yaml, with delimiter set to
"---". This might not always be the case, for example ox-hugo(a hugo
exporter for org-mode files) exports in toml format with the delimiter
set to "+++" by default.

With this change, the users will be able use frontmatter plugin to
support this toml frontmatter format.

Example usage: `Plugin.FrontMatter({delims: "+++", language: 'toml'})`

- [0] https://ox-hugo.scripter.co/doc/org-meta-data-to-hugo-front-matter/

* fixup! feat(plugins): add toml support for frontmatter

quartz/plugins/transformers/frontmatter.ts

@@ -2,14 +2,17 @@ import matter from "gray-matter"
 import remarkFrontmatter from "remark-frontmatter"
 import { QuartzTransformerPlugin } from "../types"
 import yaml from "js-yaml"
+import toml from "toml"
 import { slugTag } from "../../util/path"
 
 export interface Options {
   delims: string | string[]
+  language: "yaml" | "toml"
 }
 
 const defaultOptions: Options = {
   delims: "---",
+  language: "yaml",
 }
 
 export const FrontMatter: QuartzTransformerPlugin<Partial<Options> | undefined> = (userOpts) => {
@@ -25,6 +28,7 @@ export const FrontMatter: QuartzTransformerPlugin<Partial<Options> | undefined>
               ...opts,
               engines: {
                 yaml: (s) => yaml.load(s, { schema: yaml.JSON_SCHEMA }) as object,
+                toml: (s) => toml.parse(s) as object,
               },
             })