Add false_allow_templates as a dynamic mapping option

[bruce-hong-glean]

Description

This PR adds the dynamic: false_allow_templates option to the schema. This creates mappings for any field that matches properties or dynamic_templates, and ignores any fields that do not (as opposed to rejecting altogether).

Example from linked issue, the usage is:

1. Create the index:

{
    "properties": {
        "url": { "type": "keyword" },
    },
    "dynamic": "false_allow_templates",
    "dynamic_templates": [
        {
            "dates": {
                "match": "date_*",
                "mapping": {
                    "type": "date",
                },
            },
        }
    ]
}

2. url matches an explicit property and the fields date_timestamp and date_timezone math the dynamic template:

POST index1/_doc/1
{
  "url": "www.example.com",
  "date_timestamp": "...",
  "date_timezone": "...",
  "misc_field": "..."
}

3. Produces the mapping:

{
    "properties": {
        "url": { "type": "keyword" },
        "date_timestamp": { "type": "date" },
        "date_timezone": { "type": "date" }
    }
}

This is a redo of the reverted PR here, with invalid tests removed.

Related Issues

Resolves #18617

Check List

• Functionality includes testing.
• API changes companion pull request created
• Public documentation issue/PR created

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[github-actions]

✅ Gradle check result for a18dd07: SUCCESS

[codecov]

Codecov Report

❌ Patch coverage is 88.57143% with 4 lines in your changes missing coverage. Please review.
✅ Project coverage is 72.94%. Comparing base (dc70bf6) to head (a18dd07).
⚠️ Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
...va/org/opensearch/index/mapper/DocumentParser.java	87.09%	3 Missing and 1 partial ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##               main   #19065      +/-   ##
============================================
+ Coverage     72.87%   72.94%   +0.07%     
- Complexity    69380    69432      +52     
============================================
  Files          5647     5647              
  Lines        319084   319106      +22     
  Branches      46157    46163       +6     
============================================
+ Hits         232528   232778     +250     
+ Misses        67729    67466     -263     
- Partials      18827    18862      +35     

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[bruce-hong-glean]

cc @gaobinlong not sure if you wanted to take another look. This is an exact copy of the previous with a few test cases removed.

[andrross]

Thanks for the quick fix @bruce-hong-glean!