feat(cw): update bedrock cloudwatch dashboard

[krokoko]

Fixes #

Thanks @jimini55 for the pricing widget !

Update the bedrock CloudWatch dashboard to add the following:

• Missing runtime metrics added recently
• Add default = {} to props to avoid providing empty brackets if props not provided by user
• Create a CfnOutput with as value the URL of the created cloudwatch dashboard
• Pricing widget for a model if input/output pricing is provided by the user
• Update documentation

Tests:

Also tested to generate 2 dashboards in the same stack to make sure there is no collision in naming/id

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[MichaelWalker-git]

LGTM