Add a way to skip test on CI based on metadata

````
_quarto:
  tests-on-ci: false
````

`smoke-all.test.ts` should skip tests when this metadata is set to false inside a CI context

This can be useful for mermaid test for example

Author: cderv

dev-docs/feature-format-matrix/qmd-files/crossref/float/custom/document.qmd

@@ -7,6 +7,8 @@ crossref:
       reference-prefix: Diagram
 format:
   docusaurus-md: {}
+_quarto:
+  tests-on-ci: false 
 ---
 
 ::: {#dia-1}

dev-docs/feature-format-matrix/qmd-files/mermaid/document.qmd

@@ -2,6 +2,8 @@
 title: Mermaid
 format: 
   docusaurus-md: {}
+_quarto:
+  tests-on-ci: false 
 ---
 
 ::: {.content-visible when-format="docusaurus-md"}

tests/smoke/smoke-all.test.ts

@@ -38,6 +38,7 @@ import {
   shouldError,
   ensureHtmlElementContents,
   ensureHtmlElementCount,
+  directoryContainsOnlyAllowedPaths,
 } from "../verify.ts";
 import { readYamlFromMarkdown } from "../../src/core/yaml.ts";
 import { findProjectDir, findProjectOutputDir, outputForInput } from "../utils.ts";
@@ -46,6 +47,7 @@ import { basename, dirname, join, relative } from "../../src/deno_ral/path.ts";
 import { WalkEntry } from "../../src/deno_ral/fs.ts";
 import { quarto } from "../../src/quarto.ts";
 import { safeExistsSync, safeRemoveSync } from "../../src/core/path.ts";
+import { runningInCI } from "../../src/core/ci-info.ts";
 
 async function fullInit() {
   await initYamlIntelligenceResourcesFromFilesystem();
@@ -90,6 +92,10 @@ async function guessFormat(fileName: string): Promise<string[]> {
   return Array.from(formats);
 }
 
+function skipTestOnCi(metadata: Record<string, any>): boolean {
+  return runningInCI() && metadata["_quarto"]?.["tests-on-ci"] === false;
+}
+
 //deno-lint-ignore no-explicit-any
 function hasTestSpecs(metadata: any, input: string): boolean {
   const hasTestSpecs = metadata?.["_quarto"]?.["tests"] != undefined
@@ -285,6 +291,11 @@ for (const { path: fileName } of files) {
     ? readYamlFromMarkdown(Deno.readTextFileSync(input))
     : readYamlFromMarkdown(await jupyterNotebookToMarkdown(input, false));
 
+  if (skipTestOnCi(metadata) === true) {
+    console.log(`Skipping tests for ${input} as tests-on-ci is false in metadata`);
+    continue;
+  }
+
   const testSpecs: QuartoInlineTestSpec[] = [];
 
   if (hasTestSpecs(metadata, input)) {