Update icon after 20 years

I have worked on updating the icon of PHP on Windows,
so I need some feedback regarding the change and the
overall look.

Main reason for this change is to make the icon more
legible by means of changing the contrast and the
outline around the 'php' text, as well as having the
icon downsampled from a bigger base image which
results in anti-aliased edges, thus making this icon
adhere to modern design standards.

This change also affects how Windows platforms display
the icon in File Explorer, where previously the icon has
always defaulted to 16x16 now it can display up to
256x256.

Such change is also reflected on file assocations that
point to 'php.exe', therefore the icon for those assocations
match their "Default app".

More information on this pr:
https://github.com/php/php-src/pull/12016

Thanks.