bug#52023: 27.2; Enhancement: `this-command-invocation-(buffer|window)'

[Drew Adams]

Enhancement request: please consider adding functions
`this-command-invocation-buffer' and `this-command-invocation-window'.
(Other names OK.)

They would return, respectively, the buffer that was current, and the
window that was selected, when the command that's the value of
`this-command' was invoked.

Currently, to get this information a workaround would be to use a
`pre-command-hook' function that sets variables, and then to test those
variables.

In GNU Emacs 27.2 (build 1, x86_64-w64-mingw32)
 of 2021-03-26 built on CIRROCUMULUS
Repository revision: deef5efafb70f4b171265b896505b92b6eef24e6
Repository branch: HEAD
Windowing system distributor 'Microsoft Corp.', version 10.0.19042
System Description: Microsoft Windows 10 Pro (v10.0.2009.19042.1288)