Allow configuration of windowSize when passing a git arg

[ayyess]

• PR Description

Previously, lazygit status, log, or branch always opened in a full
window size regardless of the gui.windowSize value. Now,
gui.panelWindowSize configures the window size per arg (and no arg can
be configured as "main") regardless of requested filter path.

Closes #3042

Happy for feedback:

• Tests not added
  • I tried in pkg/integration/tests/branch/set_upstream.go but SetupConfig didn't have an effect. Should this work or is SetupConfig too late for this?
• panelWindowSize.PatternProperties is hardcoded
  • Same as windowSize
  • I tried to move permittedValues from entry_point.go to types.go to use from user_config.go but there were circular imports on integrationTypes.

• 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)
• Docs (specifically docs/Config.md) have been updated if necessary
• You've read through your own file changes for silly mistakes etc