Re-styled bhom kinter UIs

[Felix-Mallinder]

NOTE: Depends on

Issues addressed by this PR

Closes #239

Adjusted the style sheets to have a bit less 'fat'

Test files

Test against any dependant toolkits which make use of these UI elements

Changelog

Additional comments

[Tom-Kingstone]

Seems good, and looks alright when looking at it via tests

[Felix-Mallinder]

@BHoMBot check required

[bhombot-ci]

@Felix-Mallinder to confirm, the following actions are now queued:

• check code-compliance
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• check core
• check null-handling
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• check installer

There are 42 requests in the queue ahead of you.

[Tom-Kingstone]

@BHoMBot check compliance

[bhombot-ci]

@Tom-Kingstone to confirm, the following actions are now queued:

• check code-compliance
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There are 130 requests in the queue ahead of you.

[Felix-Mallinder]

@BHoMBot check ready-to-merge

[bhombot-ci]

@Felix-Mallinder to confirm, the following actions are now queued:

• check ready-to-merge

There are 154 requests in the queue ahead of you.