[sourcetree] Configure defaults

[0xdevalias]

Ref: defaults read com.torusknot.SourceTreeNotMAS

Useful things from diff after configuring things:

SUEnableAutomaticChecks = 1;
allowForcePush = 1;
bookmarksClosedOnStartup = 1;
createBookmarksOnOpenRepo = 0;
currentTheme = 1; (?dark mode?)
diffTool = 0;
globalUserEmail = "glenn@devalias.net";
globalUserFullName = "Glenn 'devalias' Grant";
terminalApp = 2; (iTerm2)