export intel_installation_path and compilervars* from tools module

[ohanar]

Changelog: Feature: Expose intel_installation_path, compilervars, compilervars_dict, and compilervars_command under tools module in order to support usage of the intel compiler.
Docs: conan-io/docs#1815

closes: #7554

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[ohanar]

The compilervars helper functions are already documented, even though they aren't exported. I added documentation for the intel_installation_path helper.

[ohanar]

Is there anything blocking merging this? I don't have permissions to view what failed on the CI, but I cannot produce any issues locally.