Contentful/cache size limit

[dpinol]

Depends on #1639 . ⚠️ Please review it first

Description

#1639 created fallback cache decorator around Contentful API which remembers forever the last successful invocation for each combination of arguments, and use its result whenever Contentful fails.
This PR adds a limit in the in memory cache size to avoid memory overflows.

Context

In case any bot adds arguments with non repeated values, the cache could grow infinitely.

Approach taken / Explain the design

• When Cache reaches 50%, 75% or 90% size, a warning is reported to the logger configured in Contentful options
• When Cache surpass the maximum size, existing cache items are deleted until the new item fits.
• In the future, we might use an external library to have a LRU cache. Not critical because typically data in CMS is small (we're not caching media, only their URLs)

To document / Usage example

The contentful plugin by default uses memoization to remember forever the last successful invocation for each combination of arguments, and use its result whenever Contentful fails. To limit the amount of memory

Testing

The pull request...

• has unit tests
• has integration tests
• doesn't need tests because... [provide a description]

[asastre]

Nice one!

[github-actions]

Unit Test Results

1 files  ±  0  2 suites   - 3   5s ⏱️ -15s
3 tests  - 17  3 ✔️  - 17  0 💤 ±0  0 ❌ ±0 

Results for commit 6d56b17. ± Comparison against base commit 63dca40.