Support regex in parameter validation

I think this is tricky to implement in the ARM runtime as there are concerns over non-performant regex, but don't know the details well enough. Also seems like it may be related to #4158. cc @jeskew as FYI

Some context below from #2922:

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Coming from the perspective of a longtime AWS CloudFormation and Terraform author now starting to use bicep - this type of password complexity validation can be achieved with a regular expression, as I've seen it done in these other tools.

So, what I think is really missing - like a SERIOUS design omission - is to have a regular expression based validation for parameters. This should have full support for all regex features, including backwards and forward references. It should support the PCRE2 standard as can be validated here: https://regex101.com

I noticed another another open issue to validate IP addresses and CIDRs, while looking to see if regex validation was an existing open issue. This is also something that can be done easily using regular expressions.

Given that this feature has been in CloudFormation templates, first JSON, then YAML, for at least 5 years that I'm personally aware of, it's sort of incredible - a glaring omission which surprised me - that this basic feature is not yet in bicep and arm. Please consider adding it, as it's incredibly useful in both preventing use of incorrect values, but also in precisely describing what values are allowed in a way beyond what's often possible to easily describe in words.

For example, I want to have a startDate parameter with the value entered as 'YYYY-MM-DD' - the fact I can't validate this simple pattern with a message to the user if they don't enter it correctly, is really surprising for a mature IaC template tool.

_Originally posted by @michael-crawford in https://github.com/Azure/bicep/issues/2922#issuecomment-1245765330_

The issue identifies ARM runtime parameter validation as the entry point and points to issues #4158 and #2922 for context. Start by reviewing those discussions and the stated PCRE2 requirement; done should mean parameters can use regex validation and report invalid values clearly without unacceptable runtime performance.

Written by the indexing model from the issue text.