build(cmake): simplify instructions (`cmake -B build && cmake --build build ...`) (#6964)

* readme: cmake . -B build && cmake --build build

* build: fix typo

Co-authored-by: Jared Van Bortel <cebtenzzre@gmail.com>

* build: drop implicit . from cmake config command

* build: remove another superfluous .

* build: update MinGW cmake commands

* Update README-sycl.md

Co-authored-by: Neo Zhang Jianyu <jianyu.zhang@intel.com>

* build: reinstate --config Release as not the default w/ some generators + document how to build Debug

* build: revert more --config Release

* build: nit / remove -H from cmake example

* build: reword debug instructions around single/multi config split

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Co-authored-by: Jared Van Bortel <cebtenzzre@gmail.com>
Co-authored-by: Neo Zhang Jianyu <jianyu.zhang@intel.com>