pgsql: Add support for Visual Studio 2019 in build scripts

Add support for Visual Studio 2019 in build scripts

This adjusts the documentation and the scripts related to the versions
of Windows SDK supported.

Author: Haribabu Kommi
Reviewed-by: Andrew Dunstan, Juan José Santamaría Flecha, Michael
Paquier
Discussion: /messages/by-id/CAJrrPGcfqXhfPyMrny9apoDU7M1t59dzVAvoJ9AeAh5BJi+UzA@mail.gmail.com
Backpatch-through: 9.4

Branch
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REL9_5_STABLE

Details
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https://git.postgresql.org/pg/commitdiff/3337fd192596973936c1cd96294f21f3c6f6e6c7

Modified Files
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doc/src/sgml/install-windows.sgml | 21 ++++++++-------
src/tools/msvc/MSBuildProject.pm | 25 ++++++++++++++++++
src/tools/msvc/README | 13 ++++-----
src/tools/msvc/Solution.pm | 28 ++++++++++++++++++++
src/tools/msvc/VSObjectFactory.pm | 55 +++++++++++++++++++++++++++++++--------
5 files changed, 115 insertions(+), 27 deletions(-)