add config.InstrumentAttributesGetter to optionally append attrs to latency instrument

[krantideep95]

This allows setting custom attributes from query context onto latency metric, like this:

otelsql.Register(databaseDriver,
	otelsql.WithInstrumentAttributesGetter(func(ctx context.Context, method otelsql.Method, query string, args []driver.NamedValue) []attribute.KeyValue {
	attrs := []attribute.KeyValue{
		semconv.DBNameKey.String(dbName),
	}

	operation, table := parseQuery(query)
	return append(attrs, semconv.DBSQLTableKey.String(table), semconv.DBOperationKey.String(operation))
  }),
)

resolves #333

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 84.2%. Comparing base (7fe66d0) to head (918fd50).
Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##            main    #334     +/-   ##
=======================================
+ Coverage   84.1%   84.2%   +0.1%     
=======================================
  Files         13      13             
  Lines        605     611      +6     
=======================================
+ Hits         509     515      +6     
  Misses        72      72             
  Partials      24      24             

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[XSAM]

@krantideep95, thanks for the PR.

It looks good to me overall. Please also update the CHANGELOG.md file to reflect this new feature.

[krantideep95]

Thanks for the review @XSAM I have updated CHANGELOG.md and accepted your suggestions.

[XSAM]

@krantideep95 Thank you for the contribution!