With IntelLLVM on Windows, we link using the compiler driver.
With MSVC on Windows, we invoke the linker directly. If we
use both in a single build tree, for separate languages,
the value of `CMAKE_LINK_DEF_FILE_FLAG` conflicts. Add a
per-language `CMAKE_<LANG>_LINK_DEF_FILE_FLAG` variable to
avoid the conflict. Preserve the language-agnostic variable
for compatibility with projects that reference it.
Fixes: #26005
Improve formatting, primarily by:
* Adding links to relevant commands, properties, generators, and so on.
* Converting code, symbols, paths, and so on to fixed-width fonts.
* Hard wrapping lines to 80 characters or less.