FLAT composition participation - wrong uniqueness lookup for id & name

[dileep-ehr]

Configuration information

<ehrbase_version>0.19.0-SNAPSHOT</ehrbase_version>
<openehr_sdk_version>1.7.0-SNAPSHOT</openehr_sdk_version>
<archie_version>1.0.4</archie_version>
<jvm_version>Ubuntu 11.0.11+9-Ubuntu-0ubuntu2.18.04</jvm_version>
<os_version>Linux amd64 5.4.0-91-generic</os_version>
<postgres_version>PostgreSQL 14.1 (Ubuntu 14.1-1.pgdg18.04+1) on x86_64-pc-linux-gnu, compiled by gcc (Ubuntu 7.5.0-3ubuntu1~18.04) 7.5.0, 64-bit</postgres_version>

Steps to reproduce

Giving the following fields for participation
```
"cbc_report/context/_participation:0|name": "Frederick Wolfstein",
"cbc_report/context/_participation:0|id": "9990",
"cbc_report/context/_participation:0|function": "performer",
"cbc_report/context/_participation:0|mode": "face-to-face communication",
"cbc_report/context/_participation:0|id_namespace": "EHR.NETWORK",
"cbc_report/context/_participation:0|id_scheme": "UUID",

If you reuse name & id values, the following is observed

Use same name and another id -  The given values are overwritten with values that match the name in the external reference table
Use same id  and another name - The given values are overwritten with values that match the id in the external reference table

So we can use any name and id only once any instance of EHRbase, which I feel will be a serious limitation.

## Actual result ##

Both name and id are considered unique in the external reference table

## Expected result (Acceptance Criteria) ##

Name and ID should not be unique as there is a chance that these could be repeated between different id_namespaces and or different id_schema within the same id_namespace. The uniqueness should be a combination of id, id_namespace & id_scheme, as you cannot have the same id for an id_scheme in any id_namespace. 

## Definition of Done ##

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