tt CLI (2.6): multiple directories with WAL files can be processed

Product: tt cli
Since: tt 2.6.0
Root document: https://www.tarantool.io/en/doc/latest/reference/tooling/tt_cli/cat/ https://www.tarantool.io/en/doc/latest/reference/tooling/tt_cli/play/
SME: @ oleg-jukovec @patapenka-alexey
Dev ticket: https://github.com/tarantool/tt/commit/529a6d94dc5a5b4f72a45c69f0faf9210171f250 https://github.com/tarantool/tt/commit/084955fd034d4b2fd5f0cfd083f2d8563f0bf1bc https://github.com/tarantool/tt/issues/1018 https://github.com/tarantool/tt/issues/1019

Details

by tt cat and tt play commands

This patch adds support of multiple directories with WAL files
to the tt cat and tt play commands.

$ tt cat /path/to/file.snap /path/to/file.xlog /path/to/dir/
$ tt play <URI> /path/to/file.snap /path/to/file.xlog /path/to/dir/

Closes #1020
Closes #1027
Requested by @patapenka-alexey in https://github.com/tarantool/tt/commit/529a6d94dc5a5b4f72a45c69f0faf9210171f250.

Read the linked tt CLI cat and play root documents first, then review the referenced commits and issues for the implemented behavior. Update both command pages to document accepting multiple directories containing WAL files, using the shell examples in the issue. Done means the cat and play documentation clearly describes and demonstrates the supported paths.