Add checksum hints to API

[dcramer]

Currently we have a 'checksum' attribute in the API. We want to deprecate that (as people shouldnt need to know how the server works), and add a new attribute which allows you to send both free-standing and templated hints.

# a completely custom fingerprint
fingerprint = ['my', 'custom', 'values']

# appending to the default value
fingerprint = ['{{default}}', 'my', 'value']

# FUTURE USE: adding additional templated params
fingerprint = ['{{default}}', '{{http.url}}', '{{http.method}}']

# client use
client.captureException(fingerprint=[...])

[mitsuhiko]

To make future use work should we error to the clients if they send \{\{[a-zA-Z0-9._]+\}\}?

[dcramer]

@mitsuhiko never error -- but we can store the hints and store errors attached to the group (though that'd be a "nice to have")

[mitsuhiko]

So just ignore an item that looks like a template.

[dcramer]

I think we'd say "if you insert a value that represents a template, and it doesnt match to a supported attribute, it effectively translates to a blank value"

[dcramer]

Available in Sentry 7.7.0