feat: adding gcp resource name span attribute

[Gautam04]

Adding a new span attribute called gcp.resource.name which contains an identifier to a particular firestore database in the following format:

//firestore.googleapis.com/projects/{project}/databases/{database_id}

Example:

//firestore.googleapis.com/projects/my_project/databases/(default)

[dconeybe]

Googlers see b/437960147 and g/firestore-sdk-team/c/uvdOjkrQ2Ns/m/1wJrFyFdAwAJ for some background details

[MarkDuckworth]

It seems like this one is missing a test. Perhaps update

nodejs-firestore/dev/system-test/tracing.ts

Line 582 in daa3d76

function expectSpanHierarchy(...spanNamesHierarchy: string[]): void {

.

[Gautam04]

It seems like this one is missing a test. Perhaps update

nodejs-firestore/dev/system-test/tracing.ts

Line 582 in daa3d76

function expectSpanHierarchy(...spanNamesHierarchy: string[]): void {

.

Have updated tests. Please check.

[Gautam04]

@MarkDuckworth @wu-hui
Could you please review this PR?