CACHE-11939: add request cf overriding cache rules compat flags

[yj7o5]

Summary

Adding a new compatibility flags: request_cf_overrides_cache_rules. The Cache team has fixed a behavior in cache recently for workers scripts that make subrequests either via the Fetch where by the cache settings in the request.cf object specified given the precedence vs Cache Rules. Up until now, for example, if cacheTtl was specified in both the worker script and a cache rule was configured to modify cacheTtl for the requested resource, cache rules would override the cacheTtl specified in the request.cf object. However, with the upcoming change, we have updated Cache such if the above flags are enabled then settings specified in the request.cf object take precedence.

Documentation checklist

• The documentation style guide has been adhered to.
• If a larger change - such as adding a new page- an issue has been opened in relation to any incorrect or out of date information that this PR fixes.

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PR Change Summary

Added compatibility flags to enhance cache behavior for Fetch and Cache APIs, allowing settings in the request.cf object to take precedence over Cache Rules.

• Introduced two new compatibility flags: request_cf_overrides_cache_rules and cache_api_request_cf_overrides_cache_rules.
• Updated cache behavior to prioritize settings in the request.cf object over Cache Rules for subrequests.
• Created documentation for the new flags, detailing their functionality and enabling conditions.

Added Files

• src/content/compatibility-flags/cache-api-request-cf-overrides-cache-rules.md
• src/content/compatibility-flags/request-cf-overrides-cache-rules.md

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[mikenomitch]

Suggested change

	This flag fixes the behavior of cache when requesting assets via the Fetch API whereby the cache settings specified in the `request.cf` object is given precedence over any Cache Rules set.
	This flag changes the behavior of cache when requesting assets via the [Fetch API](/workers/runtime-apis/fetch). Cache settings specified in the `request.cf` object, such as `cacheEverything` and `cacheTtl`, are now given precedence over any [Cache Rules]([/cache/how-to/cache-rules/) set.

[mikenomitch]

Suggested change

	With the flag enabled - either by default after 2025-03-26 or by setting the `request_cf_overrides_cache_rules` flag - any cache related settings in a Worker's `request.cf` object such as (`cacheEverything`, `cacheTtl`, etc) will override any cache rules for the target asset in subrequest.
	This flag will be enabled by default for any compatibility date after 2025-03-26.

[mikenomitch]

@yj7o5 - Added some suggestions but +1s so I'm not blocking.

Slightly more direct wording, some links, and combined two lines that were doing the same thing.

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