Add optional element type to remaining range predicates

[pbackus]

Continuation of #8819 and #8842 for isBidirectionalRange and isRandomAccessRange. Also adds missing docs for isForwardRange.

cc @atilaneves

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Testing this PR locally

If you don't have a local development environment setup, you can use Digger to test this PR:

dub run digger -- build "master + phobos#8897"

[thewilsonator]

changelog?

[pbackus]

Added a changelog entry that covers both this PR and the changes from #8842, since both will be released in 2.107.0.