[repository schema] Remove (initially: add) repository attribute for application version (initially: extension) ID

[kleihan]

Orchestra has a number of attributes for the <repository> element. One of them (applVerId) is for the application version (not to be confused with the repository version attribute version). It is proposed to add a new attribute applExtId to fully support FIX versioning covered by the FIX fields ApplVerID(1128) and ApplExtID(1156) in the StandardHeader component.

<xs:attribute name="applVerId" type="xs:string"/>
<xs:attribute name="applExtId" type="xs:integer"/>

[kleihan]

This is linked to the existing issue FIXTradingCommunity/fix-orchestra-spec#46 about DC terms to use. That may be a better approach than adding attributes to the root element.

[kleihan]

The repository element has a generic version attribute for the schema. Rather than having explicit attributes for the application, the generic DC terms should cover this information, see FIXTradingCommunity/fix-orchestra-spec#46.

Proposal is now to remove the existing applVerId attribute instead of adding a second, more granular one.