Revamped Settings, Editable Commands, Custom Prompt

This is a really useful plugin but some of the settings leave much to be desired.

Global Command Setting Changes

Ollama needs to be running and connected for the settings to open. You can easily test connection using the refresh button next to the URL.
- If you can't connect, it will look like this:
The default model is a drop down which fetches the list of installed models. (Resolves #22 )
- The default default model is now llama3 instead of llama2 (covers #28 )
Added "Prompt Template", which is a wrapper around command prompts.
- Inspired by how all the default commands used a common start and end sentence.
Added "Model Template", which is literally the template parameter of the API request sent to Ollama during a prompt. It will contain model specific tokens so its default value is empty, but the README provides an example llama3 model template.
- Model template is only applied to the default model (this is mostly due to my own oversight but I figured because most people will only use 1 model, that I wouldn't bother adding settings for model specific templates used in commands which don't use the default model).
- Sidenote, through experimentation and using the same model template as the README, specifying the text separately in the model template with an empty prompt template yielded similar conciseness to just using the default prompt template. Not relevant to my changes, but I thought it was useful information.

"Ignore prompt template?" toggle for each command (self-explanatory)
Better explanation of what temperature does.
Existing commands can be edited (resolves #13 )
You can select "Default" as the model for a command.
Removed the "Update Default Commands" setting as it didn't work and I couldn't get the DEFAULT_SETTINGS object to be overwritten between reloads of Obsidian.

Added a command "Custom prompt" which opens a form for entering a one-time custom prompt which uses the default temperature and model.
- There is a ribbon button for this command
Added a command "Save custom prompt" which saves the previous custom prompt to its own command.

Implemented 0atman's "view" to "few" typo fix (#21 )
Improved the styles of the textareas in the settings (full width, only vertical resizing).
Added information about using the new settings in the README.

P.S. the manifest.json will need to be changed back to "Ollama" after merging.