[Seal] Add new feature cxx14

[WeiDaiWD]

Describe the pull request

• What does your PR fix? Fixes #
  Added a new feature to SEAL, "cxx14", to build SEAL in C++14, which is disabled by default.

• Which triplets are supported/not supported? Have you updated the CI baseline?
  Tested x64-windows-static, x64-windows-static-md, x64-linux, x64-osx.
  x64-windows/x86-windows are not supported as the library only supports static linkage in Windows.
  No change to the CI baseline.

• Does your PR follow the maintainer guide?
  Yes

[Cheney-W]

1. Please add Port-Version: 1 after the Version: 3.6.2 line.
2. Please run .\vcpkg.exe x-add-version seal to update the json file of seal.

[Cheney-W]

@WeiDaiWD
Thanks for your so quick response. About port's json file, each of your commit changes will modify its git tree value, which means you need to update json file after you have done all the changes and executed the git commit -m "XXX" command. The specific sequence is as follows:

Git checkout -b "xxx"
Modify the local files
Git diff
Git add .
Git commit -m "comments description"
.\vcpkg x-add-version {Port name}
Git add .
Git commit -m "comments description"
git push

If you haven't executed the '. \vcpkg x-add-version {port name}' on the current branch, you need to use it after your modification is completed and submitted.
If you have executed this command on the current branch, you need to execute the following command when you need to update the json file:
.\vcpkg.exe x-add-version {port name} --overwrite-version

So, for this PR, you need to execute .\vcpkg.exe x-add-version {port name} --overwrite-version again.

[WeiDaiWD]

Thanks for the help! Hope I do it correctly this time.

[Cheney-W]

osgearth:x64-linux failure is a CI issue, it will be fixed by PR #16904.