[core] fix(Input): Mute input shadows

[CPerinet]

Make input inner shadows a bit more muted to balance visual weight. When used in high density UIs, input stand-out as too noisy visually.

Before	After

[adidahiya]

@CPerinet your branch is behind develop quite a bit. Can you merge origin/develop? That will fix the test infra build failure.

Have you tested this reduced shadow in low contrast environments like projectors screens?

Does this change affect our high-contrast styles at all?

blueprint/packages/core/src/components/forms/_common.scss

Line 126 in 7897e39

border: 1px solid $pt-high-contrast-mode-border-color;

[adidahiya]

To answer my own question: this does not have any effect on the high contrast stylesheet, I tested in Windows:

But this did reveal a separate (unrelated) issue where the "High Contrast White" borders are poorly styled: