VS: Do not apply any '/external:*' flag table mapping on VS < 16.10

Since commit 887e9df0 (VS: Update v142 CL flag table for VS 16.10,
2021-06-04) we map several `/external:*` flags to their corresponding
`.vcxproj` elements.  These elements were added to `cl.xml` in VS 16.10,
so filter them out in older VS versions.  Add a field to the json flag
table format to specify the minimum version of VS needed for a given
mapping.

Issue: #22308
37 jobs for !6241 with vs-flag-tables in 50 minutes and 55 seconds (queued for 3 seconds)
latest detached
Status Job ID Name Coverage
  Build
manual #5883642
linux docker build cmake manual
build:centos6-x86_64
manual #5883643
linux-3.17 linux docker build cmake manual
build:fedora34-ninja
manual #5883645
nonconcurrent xcode-12.5 shell macos cmake manual
build:macos-x86_64-makefiles
manual #5883644
nonconcurrent xcode-12.5 shell macos cmake manual
build:macos-x86_64-ninja
passed #5883646
nonconcurrent msvc-19.29-16.10 vs2019 shell windows cmake manual
build:windows-vs2019-x64-ninja

00:12:01

passed #5883638
linux docker build cmake
lint:codespell

00:00:27

passed #5883639
linux docker build cmake
lint:debian10-iwyu

00:01:58

passed #5883641
linux-3.17 linux docker build cmake
lint:fedora34-sphinx

00:03:34

passed #5883640
linux-3.17 linux docker build cmake
lint:fedora34-tidy

00:06:13

 
  Test
created #5883647
x11 linux-3.17 linux docker cmake
test:fedora34-ninja
created #5883649
nonconcurrent xcode-12.5 shell macos cmake
test:macos-x86_64-makefiles
created #5883648
nonconcurrent xcode-12.5 shell macos cmake
test:macos-x86_64-ninja
passed #5883650
nonconcurrent msvc-19.29-16.10 vs2019 shell windows cmake
test:windows-vs2019-x64-ninja

00:21:14

 
  Test Ext
created #5883653
linux docker cuda-rt cmake
test:cuda10.2-nvidia
created #5883651
linux-3.17 linux docker build cmake
test:debian10-ninja
created #5883652
linux-3.17 linux docker build cmake
test:fedora34-makefiles
created #5883654
linux-3.17 linux docker build cmake
test:fedora34-ninja-multi
created #5883655
concurrent xcode-12.5 shell macos cmake
test:macos-x86_64-xcode
passed #5883656
concurrent msvc-19.29-16.10 vs2019 shell windows cmake
test:windows-vs2019-x64

00:11:25

 
  External
passed cdash

passed ghostflow-check-master

passed ghostflow-check-release

passed ghostflow-stager

passed cdash

passed cdash

passed cdash

passed ghostflow-check-master

passed ghostflow-stager

passed ghostflow-stager

passed ghostflow-stager

passed ghostflow-stager

passed ghostflow-stager

passed ghostflow-stager

passed ghostflow-stager

passed ghostflow-stager

passed ghostflow-stager

passed ghostflow-stager