Feature Request: Website monitoring improvements

## Is your feature request related to a problem? Please describe.
The HTTP(S) monitoring options are now quite limited. I would like to suggest some improvements. Checkmate is already an amazing tool but I feel like the following changes would elevate the website monitoring to the next level.
Thank you to all the contributors. 😄

## Describe the solution you'd like
**1. Authentication support**
Some applications require authentication in the form of an Authorization header. Adding support for authentication in the form of basic authentication or other authentication or token headers would be nice. mTLS or OAuth2 support would be even better.

**2. Custom header support**
This could go hand-in-hand with the authentication support. Some applications require additional headers to be present before giving back a succesful (20x) status.

**3. Other methods**
Some endpoints I would like to monitor only support POST, PUT or DELETE methods.

**4. Retries**
When monitoring public resources, an incidental failed request happens. I would like to be able to set the amount of failures before an incident is created and notification is sent.

**5. Uptime overview**
In the Uptime overview it is now shown as *HTTP(S)*. Showing HTTP or HTTPS there would be a nice bonus.

**6. Custom body**
Adding custom body to request. Could be useful, other monitoring solutions support this as well.

**7. Custom intervals**
Right now, only 1 through 5 minute intervals are available. It would be nice to be able to set more precise intervals. For example by changing it from a drop-down to an input of seconds.