Add configurable padding and focus text for some widgets

[schiltz3]

Add attributes to the standard widgets allowing their text and padding to be modified in the config.

NOTE: The added attributes have default values corresponding to their original hard-coded values, so this is backward compatible.

---

1. Edit or remove padding characters around edges of widget elements:

Before:   

After:    

2. Change active monitor character and active layout padding

Before:   

After:    

[N1x0]

I like the ability to set padding, I'd just move it to IBarWidgetPart and then implement in the individual widgets as necessary. Also IMO defaults should not have any padding, I know this is up to personal preference, just stating mine.

If you could make the necessary changes I'll approve them, thanks for the PR!

[schiltz3]

I believe I made the changes you suggested.

The default padding has been removed. I can add it back in if we think it is outside the scope of this PR.

I did not change the Focus/Unfocus text, but I think it could be changed to the focus text being the text attribute, and hard coding unfocused to be an empty string.

LMK what you think

[N1x0]

Changes look good to me, I also agree that FocusedMonitorWidget should return something meaningful instead of just '****' or "", but I think that's better kept in a seperate PR. I will write something in the docs to reflect the change. Please have a look there as well as the author ;)

[dalyIsaac]

I agree with @N1x0 - otherwise LGTM!

[schiltz3]

Changes look good to me, I also agree that FocusedMonitorWidget should return something meaningful instead of just '****' or "".

I may update the docs later with examples of how to use Extended Unicode with workspacer. With fonts like FontAwsome

[katuwiran]

I love this PR because since day 1 I've always customized the padding (and needed to recompile workspacer everytime it updates).

However, a padding set to an empty string ("") instead of with a space (" ") leads to this behavior:

padding.issues.mp4

because of an inconsistency in line 88 of WorkspaceWidget.cs:
return visible ? LeftPadding + workspace.Name + RightPadding : $" {workspace.Name} ";

If both padding variables are "", then once you focus on a workspace its length shrinks on the bar.

I would've liked to submit a fix myself, but I'm still not comfortable with Git and programming in general.