deploy generator: use copy() rather than copyfile()

[tmwa]

fixes #5135

Changelog: Bugfix: Use copy() for deploy generator so that permissions of files are preserved. Required if you want to use the deploy generator to deploy executables.

Docs: omit

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[danimtb]

It would deserve an integration test with the use case of the original issue

[tmwa]

Personally I don't have a lot of time to look into how to add and write an integration test. The change is small enough to do without imo.

[danimtb]

@tmwa no problem, I would contribute the test for you 😄

[memsharded]

Merged! Thanks @tmwa for the contribution, it will be released in next Conan 1.16