fix(database,functions): custom endpoint CONTAIN op and PUT route mapping

[kkopanidis]

Summary

Custom endpoint comparison operation 8 was documented as array-contains but generated the same $nin query as operation 7, so filters never matched documents whose array fields include a value. Functions declared with inputs.method: 'PUT' also registered as GET routes because getOperation only handled the UPDATE alias.

• Remove the erroneous op 8 $nin branch so CONTAIN uses the default direct-equality query
• Treat PUT the same as UPDATE when registering function routes

What kind of change does this PR introduce?

• Bugfix
• Feature
• Code style update
• Refactor
• Build-related changes
• Other (please describe)

Does this PR introduce a breaking change?

• Yes
• No

The PR fulfills these requirements:

• It's submitted to the main branch
• When resolving a specific issue, it's referenced in the PR's description

Test plan

• Create a custom endpoint with an array field filter using comparison op 8 and confirm matching documents are returned (op 7 with the same value should still use exclusion semantics)
• Register a request function with inputs.method: 'PUT' and confirm the router exposes PUT on the function path
• Send an HTTP PUT to that function path and confirm the handler runs; GET on the same path should not invoke the PUT handler