Add ES|QL bit_length function (elastic#115792)

Author: timgrein

docs/changelog/115792.yaml

@@ -0,0 +1,5 @@
+pr: 115792
+summary: Add ES|QL `bit_length` function
+area: ES|QL
+type: enhancement
+issues: []

docs/reference/esql/functions/description/bit_length.asciidoc

@@ -8,6 +8,7 @@
 {esql} supports these string functions:
 
 // tag::string_list[]
+* <<esql-bit_length>>
 * <<esql-concat>>
 * <<esql-ends_with>>
 * <<esql-from_base64>>
@@ -30,6 +31,7 @@
 * <<esql-trim>>
 // end::string_list[]
 
+include::layout/bit_length.asciidoc[]
 include::layout/concat.asciidoc[]
 include::layout/ends_with.asciidoc[]
 include::layout/from_base64.asciidoc[]

docs/reference/esql/functions/examples/bit_length.asciidoc

@@ -82,8 +82,10 @@ tasks.named("precommit").configure {
 
 tasks.named("yamlRestCompatTestTransform").configure({ task ->
   task.skipTest("security/10_forbidden/Test bulk response with invalid credentials", "warning does not exist for compatibility")
-  task.skipTest("inference/inference_crud/Test get all", "Assertions on number of inference models break due to default configs")
   task.skipTest("esql/60_usage/Basic ESQL usage output (telemetry)", "The telemetry output changed. We dropped a column. That's safe.")
+  task.skipTest("inference/inference_crud/Test get all", "Assertions on number of inference models break due to default configs")
+  task.skipTest("esql/60_usage/Basic ESQL usage output (telemetry) snapshot version", "The number of functions is constantly increasing")
+  task.skipTest("esql/60_usage/Basic ESQL usage output (telemetry) non-snapshot version", "The number of functions is constantly increasing")
   task.skipTest("esql/80_text/reverse text", "The output type changed from TEXT to KEYWORD.")
   task.skipTest("esql/80_text/values function", "The output type changed from TEXT to KEYWORD.")
 })