Add space to the Post Schedule date

[Soean]

Description

Adds space between Post Schedule label and date
Resolve #3138

Screenshots:

Before:

After:

[aduth]

This looks like a good idea, but I think the styling should be applied to children of components-panel__row generally, not specific to the schedule toggle.

https://github.com/WordPress/gutenberg/blob/master/components/panel/style.scss

[codecov]

Codecov Report

Merging #3188 into master will decrease coverage by 0.44%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #3188      +/-   ##
==========================================
- Coverage   31.61%   31.17%   -0.45%     
==========================================
  Files         217      235      +18     
  Lines        6278     6534     +256     
  Branches     1116     1163      +47     
==========================================
+ Hits         1985     2037      +52     
- Misses       3609     3773     +164     
- Partials      684      724      +40

Impacted Files	Coverage Δ
editor/sidebar/post-author/index.js	0% <0%> (-85%)	⬇️
editor/sidebar/post-pending-status/index.js	0% <0%> (-58.34%)	⬇️
blocks/library/gallery/gallery-image.js	0% <0%> (-55.56%)	⬇️
editor/sidebar/post-sticky/index.js	0% <0%> (-54.55%)	⬇️
blocks/library/gallery/index.js	36.84% <0%> (-25.66%)	⬇️
blocks/library/image/index.js	52.38% <0%> (-12.33%)	⬇️
components/navigable-menu/index.js	25.92% <0%> (-2.08%)	⬇️
editor/selectors.js	94.38% <0%> (-1.27%)	⬇️
blocks/library/gallery/block.js	10% <0%> (-1.12%)	⬇️
editor/utils/dom.js	15.2% <0%> (-0.91%)	⬇️
... and 86 more

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[Soean]

@aduth You are right, thats a better idea. I added the styling to .components-panel__row label and added the missing labels to post-schedule and post-visibility. I also added a id to the Dropdown component.

[aduth]

There are some issues with the labeling changes (which I'd also have recommended to create a separate pull request for):

• With component patterns as in React, we don't want to assume that there is a single instance of an element on a page, and since id must be globally unique, 'post-visibility-selector' is not a good ID. For these cases we created the withInstanceId higher-order component to generate unique IDs to use as suffixes.
• Since Dropdown expects the developer to implement renderToggle with a button, we don't need it to accept an id prop and rather can apply the id on the button returned in renderToggle (in PostSchedule and in PostVisibility).

[Soean]

I created a separate pull request for the labels: #3317, so this one has to be merged first.
This PR only adds space to the panel row labels and align the post schedule text.

[aduth]

Looks good 👍