Remove PIKA_MOVE and PIKA_FORWARD

[msimberg]

The macros were originally introduced to avoid the template instantiation overhead of std::move and std::forward, as well as the debug bloat. Both clang and GCC should nowadays treat them as builtins, though perhaps not on all supported compiler versions. Since the original change was simply a build-time optimization I think it's fair to go back to the std:: functions again.

The benefit is that tooling like clang-tidy can warn about improper uses of the functions.

The one downside of using std::move over PIKA_MOVE (which is simply a cast to a non-const r-value reference) is that std::move will happily create const&& types, where that is almost never intended for a move.

[msimberg]

This PR has lower priority than others, so in case of conflicts let's try to merge others first and push this when it's a bit more quiet on the PR-front.

[codacy-production]

Coverage summary from Codacy

See diff coverage on Codacy

Coverage variation	Diff coverage
✅ +0.06% (target: -1.00%)	❌ 85.58% (target: 90.00%)

Coverage variation details

	Coverable lines	Covered lines	Coverage
Common ancestor commit (81d29bf)	18274	13788	75.45%
Head commit (41f7191)	18272 (-2)	13797 (+9)	75.51% (+0.06%)

Coverage variation is the difference between the coverage for the head and common ancestor commits of the pull request branch: <coverage of head commit> - <coverage of common ancestor commit>

Diff coverage details

	Coverable lines	Covered lines	Diff coverage
Pull request (#1325)	631	540	85.58%

Diff coverage is the percentage of lines that are covered by tests out of the coverable lines that the pull request added or modified: <covered lines added or modified>/<coverable lines added or modified> * 100%

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