fix(material/datepicker): prevent touch UI overflow

[Will-thom]

Summary

• Constrain the touch datepicker content container to the dialog viewport height.
• Allow the touch content container to scroll when short viewports cannot fit the full calendar.
• Add a regression spec that verifies the touch container is bounded and scrollable.

Fixes #33115.

Testing

• pnpm exec sass --load-path=src src/material/datepicker/datepicker-content.scss
• pnpm exec stylelint src/material/datepicker/datepicker-content.scss --config .stylelintrc.json
• pnpm exec prettier --check src/material/datepicker/datepicker-content.scss src/material/datepicker/datepicker.spec.ts
• pnpm bazel test //src/material/datepicker:unit_tests was attempted locally, but the Windows environment failed before running tests while fetching/configuring browser/Sass Bazel toolchains.