In Qiskit#5582 we added a script that is used to ensure we don't import
slow optional dependencies in the default 'import qiskit' path. Since
that PR merged we've managed to remove a few more packages from the
default import path (see Qiskit#5619, Qiskit#5485, and Qiskit#5620) which we should add
the same checks to to ensure we don't regress and accidently start
importing them again in the default path. This commit adds all these
packages to the list of imports not allowed as part of 'import qiskit'.

In #5582 we added a script that is used to ensure we don't import
slow optional dependencies in the default 'import qiskit' path. Since
that PR merged we've managed to remove a few more packages from the
default import path (see #5619, #5485, and #5620) which we should add
the same checks to to ensure we don't regress and accidently start
importing them again in the default path. This commit adds all these
packages to the list of imports not allowed as part of 'import qiskit'.

…t#5620)

* Add a lazy loading wrapper class for __qiskit_version__

This commit migrates the __qiskit_version__ module attribute away from
using a dict constructed at import time to being an instance of a lazy
loading class that will import the elements to get their version
information only at run time if needed. This will improve the overall
import performance and also reduce the possibility of introducing an
import cycle when we remove namespace packaging.

Related to Qiskit/qiskit#5100 and Qiskit/qiskit#5532

* Rename qiskit.execute module to qiskit.execute_function

The qiskit.execute module has a name conflict with the re-exported
path to it's sole public function qiskit.execute(). Whether python uses
the module or the function is an import time race condition and by
making the element imports occur at runtime this switches the normal
evaluation to use the module instead of the function. However, this was
always a bug and could have been triggered in other ways too. To make
the imports deterministic either the function or the module needs to be
renamed and since the module is less commonly used than the function
that is renamed.

* Rename qiskit.compiler inner modules to avoid name conflict

The qiskit.compiler module has a name conflict with the re-exported
path to public functions qiskit.compiler. Whether python uses
the module or the function is an import time race condition, amd
could be triggered by subtle changes in import evaluation order. To make
the imports deterministic either the function or the module needs to be
renamed and since the module is less commonly used than the function
that is renamed.

* Fix docs build

* Apply suggestions from code review

Co-authored-by: Kevin Krsulich <[email protected]>