blob: fix gutters style conflicts

[taras-yemets]

1. Places code folding gutters before the blame decorations gutter.
   Note: Blame decorations can't go before the code folding gutters because of the way the former is implemented (TL;DR: blame decorations are not in the gutter, but inside the line, see https://github.com/sourcegraph/sourcegraph/pull/44148#issue-1442079069).
2. Sets minimum height for selected lines layer markers to match the increased line height when the blame decorations are visible.
3. Removes focus styles from .cm-content (redundant blue line below the content reported in Slack).
4. Removes selection layer overflow reported in Slack.

Though some of these changes seem unrelated I put them in a single PR because all of them originate from selected text and lines layers configuration.

Screen.Recording.2023-02-08.at.18.35.57.mov

Test plan

Tested manually (video attached).

App preview:

• Web

Check out the client app preview documentation to learn more.

[sg-e2e-regression-test-bob]

Bundle size report 📦

Initial size	Total size	Async size	Modules
0.00% (0.00 kb)	0.00% (+0.29 kb)	0.00% (+0.29 kb)	0.00% (0)

Look at the Statoscope report for a full comparison between the commits cf8f11b and 0b2dca3 or learn more.

Open explanation

• Initial size is the size of the initial bundle (the one that is loaded when you open the page)
• Total size is the size of the initial bundle + all the async loaded chunks
• Async size is the size of all the async loaded chunks
• Modules is the number of modules in the initial bundle

[taras-yemets]

Addressing https://github.com/sourcegraph/sourcegraph/pull/46765#discussion_r1090865185

[valerybugakov]

Wow, this is tricky indeed!