Set shared capability of Mini Moka and OPFS

[QazCetelic]

Which issue does this PR close?

Closes #7855.

Rationale for this change

The shared capability flag is set for all other services, but is missing for OPFS and Mini Moka.
The choice to mark one shared and the other not is based on Xuanwo's definition in this comment.

What changes are included in this PR?

1. Set mini moka backend shared capability to false
2. Set opfs backend shared capability to true

Are there any user-facing changes?

opfs shared capability becomes true instead of defaulting to false.

AI Usage Statement

No AI used

[Xuanwo]

false doesn't need to be set.

[QazCetelic]

Yes, I decided to also set it because all other services also explicitly set it to false.

opendal/core/services/cacache/src/backend.rs

Line 65 in 4f1df12

shared: false,

opendal/core/services/cloudflare-kv/src/backend.rs

Line 174 in 4f1df12

shared: false,

opendal/core/services/dashmap/src/backend.rs

Line 101 in 4f1df12

shared: false,

opendal/core/services/moka/src/backend.rs

Line 205 in 4f1df12

shared: false,

opendal/core/services/persy/src/backend.rs

Line 139 in 4f1df12

shared: false,

opendal/core/services/redb/src/backend.rs

Line 151 in 4f1df12

shared: false,

opendal/core/services/rocksdb/src/backend.rs

Line 101 in 4f1df12

shared: false,

opendal/core/services/sled/src/backend.rs

Line 125 in 4f1df12

shared: false,

opendal/core/services/sqlite/src/backend.rs

Line 191 in 4f1df12

shared: false,

I can add a commit to remove those lines if you'd prefer avoiding setting implicitly defined capabilities.