Allow changing diff context size and rename threshold when main view is focused

[stefanhaller]

• PR Description

Allow pressing {, }, (, and ) to change the diff context size and rename threshold when the main view is focused. This was forgotten in #4429.

Labeling as ignore-for-release because it can be considered a bug in #4429, which isn't released yet.

• Please check if the PR fulfills these requirements

• Cheatsheets are up-to-date (run go generate ./...)
• Code has been formatted (see here)
• Tests have been added/updated (see here for the integration test guide)
• Text is internationalised (see here)
• If a new UserConfig entry was added, make sure it can be hot-reloaded (see here)
• Docs have been updated if necessary
• You've read through your own file changes for silly mistakes etc

[codacy-production]

Coverage summary from Codacy

See diff coverage on Codacy

Coverage variation	Diff coverage
Report missing for aa688851	✅ 93.75%

Coverage variation details

	Coverable lines	Covered lines	Coverage
Common ancestor commit (aa68885)	Report Missing	Report Missing	Report Missing
Head commit (da24deb)	55899	48493	86.75%

Coverage variation is the difference between the coverage for the head and common ancestor commits of the pull request branch: <coverage of head commit> - <coverage of common ancestor commit>

Diff coverage details

	Coverable lines	Covered lines	Diff coverage
Pull request (#4505)	32	30	93.75%

Diff coverage is the percentage of lines that are covered by tests out of the coverable lines that the pull request added or modified: <covered lines added or modified>/<coverable lines added or modified> * 100%

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Footnotes

1. Codacy didn't receive coverage data for the commit, or there was an error processing the received data. Check your integration for errors and validate that your coverage setup is correct. ↩

[jesseduffield]

LGTM