[clang] Add test for CWG1822

[[https://wg21.link/p1787 | P1787]]: CWG1822 is resolved by specifying that the body of a lambda remains in the surrounding (function parameter) scope.
Wording: A parameter-declaration-clause P introduces a function parameter scope that includes P. <...> If P is associated with a lambda-declarator, its scope extends to the end of the compound-statement in the lambda-expression. ([basic.scope.param])

Reviewed By: #clang-language-wg, shafik

Differential Revision: https://reviews.llvm.org/D147836