Improve CI with Eask

[jcs090218]

I have recently created a tool named Eask. It's similar to Cask, but it has a better cross-platform capability. It tests your package/configuration in a much more consistent way.

Related PR already applied:

• https://github.com/emacs-lsp/lsp-ui/pull/700
• https://github.com/emacs-lsp/dap-mode/pull/596
• https://github.com/emacs-lsp/lsp-dart/pull/158

Changes from this PR:

• Merge jobs unix-test and windows-test
• Add test for Emacs version 27.2 and 28.1
• Remove test/windows-bootstrap.el
• Add Eask-file for CI test
• Add checkdoc test
• Add package-lint test

[jcs090218]

@danielmartin Any chance to review this? :)