treewide: standardize shell integration options

[trueNAHO]

Description

Standardize all 'programs.<PROGRAM>.enable<SHELL>Integration' options
with the following new functions:

- lib.hm.shell.mkBashIntegrationOption
- lib.hm.shell.mkFishIntegrationOption
- lib.hm.shell.mkIonIntegrationOption
- lib.hm.shell.mkNushellIntegrationOption
- lib.hm.shell.mkZshIntegrationOption

These functions should default to their corresponding global option:

- shell.enableBashIntegration
- shell.enableFishIntegration
- shell.enableIonIntegration
- shell.enableNushellIntegration
- shell.enableZshIntegration

All these global options default to the 'shell.enableShellIntegration'
value.

This hierarchy standardizes the shell integration and increases end-user
flexibility.

BREAKING CHANGE: This modifies the following inconsistent default values
from 'false' to 'true':

- programs.zellij.enableBashIntegration
- programs.zellij.enableFishIntegration
- programs.zellij.enableZshIntegration

Checklist

• Change is backwards compatible.

• Code formatted with ./format.

• Code tested through nix-shell --pure tests -A run.all
  or nix build --reference-lock-file flake.lock ./tests#test-all using Flakes.

• Test cases updated/added. See example.

• Commit messages are formatted like

  {component}: {description}
  
  {long description}
  

  See CONTRIBUTING for more information and recent commit messages for examples.

• If this PR adds a new module

  • Added myself as module maintainer. See example.

Maintainer CC

[rycee]

Very cool, thanks for the contribution! I've added a few minor comments.

[rycee]

Unfortunately cannot allow default or example to be affected by the configuration since it would in turn affect the documentation build. Can resolve it by adding a defaultText and make the example hard-coded. Something like this (untested) perhaps

Suggested change

	example = !default;
	defaultText = literalExpression "config.shell.enableShellIntegration";
	example = false;

[rycee]

Can sort the field in the more idiomatic way (also fix the overridden typo 🙂):

Suggested change

	default = true;
	description = ''
	Whether to enable shell integration for all supported shells.
	Individual shell integrations can be overriden with their respective
	`shell.enable<SHELL>Integration` option. For example, the following
	declaration globally disables shell integration for Bash:
	```nix
	config.shell.enableBashIntegration = false;
	```
	'';
	example = false;
	type = lib.types.bool;
	type = lib.types.bool;
	default = true;
	example = false;
	description = ''
	Whether to enable shell integration for all supported shells.
	Individual shell integrations can be overridden with their respective
	`shell.enable<SHELL>Integration` option. For example, the following
	declaration globally disables shell integration for Bash:
	```nix
	config.shell.enableBashIntegration = false;
	```
	'';

[rycee]

I think you can put this together with the other enable<shell>Integration options above.