fix: file references inside .pbxproject are incorrect when there's space in project path

[Fatme]

{N} CLI is not able to build a native project in case when the project name contains a space. In this case the filePaths inside HEADER_SEARCH_PATHS sections are not valid. Actually this PR fixes 2 problems.
The first is that the added filePath is full file path, so this PR changes this and makes the paths relative.
The second thing is that the filePath does not contain " ", so this PR adds "" around the filePath.

Steps to reproduce:

1. tns create "my space app"
2. Change the version of tns-core-modules to next
3. tns build ios

PR Checklist

• The PR title follows our guidelines: https://github.com/NativeScript/NativeScript/blob/master/CONTRIBUTING.md#commit-messages.
• There is an issue for the bug/feature this PR is for. To avoid wasting your time, it's best to open a suggestion issue first and wait for approval before working on it.
• You have signed the CLA.
• All existing tests are passing: https://github.com/NativeScript/nativescript-cli/blob/master/CONTRIBUTING.md#contribute-to-the-code-base
• Tests for the changes are included.

[Fatme]

run ci

[Natalia-Hristova]

run ci

[Fatme]

run ci

[dtopuzov]

run ci

[Natalia-Hristova]

run ci