Add NodeJS script to check mermaid

What does this MR do and why?

This MR adds a mermaid linter to check for Syntax errors in doc/**/*.md.

See #441248 (closed)

Draft?

• See self-review
• Run script in CI on doc/* changes
• Run script in lefthook

MR acceptance checklist

Please evaluate this MR against the MR acceptance checklist. It helps you analyze changes to reduce risks in quality, performance, reliability, security, and maintainability.

Screenshots or screen recordings

Lefthook example

How to set up and validate locally

After master

$ time scripts/lint/check_mermaid.mjs
Checking 2295 markdown files...

real    0m2.347s
user    0m2.654s
sys     0m0.304s

$ time scripts/lint/check_mermaid.mjs "doc/**/*.md"
Checking 2241 markdown files...

real    0m1.615s
user    0m2.052s
sys     0m0.139s

Before !144322 (merged)

git revert -m 1 3f32c1e5

scripts/lint/check_mermaid.mjs

Checking 2295 markdown files...
doc/architecture/blueprints/gitlab_services/index.md:109: Mermaid syntax error
Error: Error: Parse error on line 4:
...<.. "*" Environment :    Environment "*
-----------------------^
Expecting 'NEWLINE', 'EOF', 'SQS', 'STR', 'GENERICTYPE', 'LABEL', 'STRUCT_START', 'STRUCT_STOP', 'STYLE_SEPARATOR', 'ANNOTATION_END', 'AGGREGATION', 'EXTENSION', 'COMPOSITION', 'DEPENDENCY', 'LOLLIPOP', 'LINE', 'DOTTED_LINE', 'CALLBACK_NAME', 'HREF', 'ALPHA', 'NUM', 'MINUS', 'UNICODE_TEXT', 'BQUOTE_STR', got 'COLON'

doc/development/gitlab_flavored_markdown/specification_guide/index.md:679: Mermaid syntax error
Error: Error: Parse error on line 15:
...endsubgraph output:<br/>test results/ou
----------------------^
Expecting 'SEMI', 'NEWLINE', 'SPACE', 'EOF', 'GRAPH', 'DIR', 'subgraph', 'SQS', 'end', 'AMP', 'COLON', 'START_LINK', 'STYLE', 'LINKSTYLE', 'CLASSDEF', 'CLASS', 'CLICK', 'DOWN', 'UP', 'NUM', 'NODE_STRING', 'BRKT', 'MINUS', 'MULT', 'UNICODE_TEXT', got 'TAGSTART'

doc/development/gitlab_flavored_markdown/specification_guide/index.md:755: Mermaid syntax error
Error: Error: Parse error on line 8:
...endsubgraph output:<br/>test results/ou
----------------------^
Expecting 'SEMI', 'NEWLINE', 'SPACE', 'EOF', 'GRAPH', 'DIR', 'subgraph', 'SQS', 'end', 'AMP', 'COLON', 'START_LINK', 'STYLE', 'LINKSTYLE', 'CLASSDEF', 'CLASS', 'CLICK', 'DOWN', 'UP', 'NUM', 'NODE_STRING', 'BRKT', 'MINUS', 'MULT', 'UNICODE_TEXT', got 'TAGSTART'

Total errors: 3
To fix these errors, see https://docs.gitlab.com/ee/development/documentation/testing.html#mermaid.

real    0m2.347s
user    0m2.654s
sys     0m0.304s