This PR improves the logging module a tad bit along with the
documentation.
**New Look:**
## Usage
**General Logger**
InvokeAI has a module level logger. You can call it this way.
In this below example, you will use the default logger `InvokeAI` and
all your messages will be logged under that name.
```python
from invokeai.backend.util.logging import logger
logger.critical("CriticalMessage") // In Bold Red
logger.error("Info Message") // In Red
logger.warning("Info Message") // In Yellow
logger.info("Info Message") // In Grey
logger.debug("Debug Message") // In Grey
```
Results:
```
[12-05-2023 20]::[InvokeAI]::CRITICAL --> This is an info message [In Bold Red]
[12-05-2023 20]::[InvokeAI]::ERROR --> This is an info message [In Red]
[12-05-2023 20]::[InvokeAI]::WARNING --> This is an info message [In Yellow]
[12-05-2023 20]::[InvokeAI]::INFO --> This is an info message [In Grey]
[12-05-2023 20]::[InvokeAI]::DEBUG --> This is an info message [In Grey]
```
**Custom Logger**
If you want to use a custom logger for your module, you can import it
the following way.
```python
from invokeai.backend.util.logging import logging
logger = logging.getLogger(name='Model Manager')
logger.critical("CriticalMessage") // In Bold Red
logger.error("Info Message") // In Red
logger.warning("Info Message") // In Yellow
logger.info("Info Message") // In Grey
logger.debug("Debug Message") // In Grey
```
Results:
```
[12-05-2023 20]::[Model Manager]::CRITICAL --> This is an info message [In Bold Red]
[12-05-2023 20]::[Model Manager]::ERROR --> This is an info message [In Red]
[12-05-2023 20]::[Model Manager]::WARNING --> This is an info message [In Yellow]
[12-05-2023 20]::[Model Manager]::INFO --> This is an info message [In Grey]
[12-05-2023 20]::[Model Manager]::DEBUG --> This is an info message [In Grey]
```
**When to use custom logger?**
It is recommended to use a custom logger if your module is not a part of
base InvokeAI. For example: custom extensions / nodes.
1. if retrieving an item from the queue raises an exception, the
InvocationProcessor thread crashes, but the API continues running in
a non-functional state. This fixes the issue
2. when there are no items in the queue, sleep 1 second before checking
again.
3. Also ensures the thread isn't crashed if an exception is raised from
invoker, and emits the error event
Intentionally using base Exceptions because for now we don't know which
specific exception to expect.
Fixes (sort of)? #3222
