DOC-2324: Add workflows for development on 5 docs branch

[MitchC1999]

Ticket: DOC-2324

Site: Staging branch

Changes:

• Added development and codeql workflows which apply to branches and PRs against tinymce/5 branch

Pre-checks:

• Branch prefixed with feature/5/ or hotfix/5/

Review:

• Documentation Team Lead has reviewed

[kemister85]

@MitchC1999 LGTM, but can you check the below:
`[05:41:23.761] WARN (asciidoctor): id assigned to section already in use: each
file: /home/runner/work/tinymce-docs/tinymce-docs/modules/ROOT/pages/apis/tinymce.dom.domquery.adoc:364
source: /home/runner/work/tinymce-docs/tinymce-docs (branch: HEAD | start path: .)

[05:41:23.817] ERROR (asciidoctor): target of xref not found: apis/tinymce.core.dom.domquery.adoc
file: /home/runner/work/tinymce-docs/tinymce-docs/modules/ROOT/pages/apis/tinymce.dom.domquery.adoc
source: /home/runner/work/tinymce-docs/tinymce-docs (branch: HEAD | start path: .)

[05:41:24.107] ERROR (asciidoctor): target of xref not found: apis/tinymce.editormanager.adoc
file: /home/runner/work/tinymce-docs/tinymce-docs/modules/ROOT/pages/apis/tinymce.editor.adoc
source: /home/runner/work/tinymce-docs/tinymce-docs (branch: HEAD | start path: .)`

[MitchC1999]

@kemister85 Those errors are from the api docs, where on 5 there are a couple of apis missing (private), renamed, or with duplicate names. These same errors appear on the current 5 antora docs. They're just something to be aware of, but we will expect these 3 errors to always appear. We can work on removing them at a later date, but it would require a change to moxiedoc or to the 5 branch, so it will take a lot of effort.