feat: additional kyc check for review stage (#138)

Closes NEAR-DevHub/neardevhub-bos#848 - adds
additional kyc check for review stage.

For that, VersionedTimelineStatus along with TimelineStatusV2 is
introduced

Also it removes posts functionality for the following reason:
```bash
Action #0: ExecutionError("Exceeded the prepaid gas.")
```
It arises on calling either `unsafe_self_upgrade` or `unsafe_migrate` on
`test_deploy_contract_self_upgrade` test. Because code size is too big. So
code for posts was removed.

src/common/mod.rs

@@ -0,0 +1,39 @@
+use near_sdk::serde::{Deserialize, Serialize};
+use near_sdk::borsh::{BorshDeserialize, BorshSerialize};
+use near_sdk::{NearSchema, BorshStorageKey, CryptoHash};
+
+#[derive(BorshSerialize, BorshDeserialize, Serialize, Deserialize, Clone, NearSchema)]
+#[serde(crate = "near_sdk::serde")]
+#[serde(tag = "post_version")]
+#[borsh(crate = "near_sdk::borsh")]
+pub enum VersionedPost {
+    V0,
+}
+
+
+#[derive(BorshSerialize, BorshStorageKey)]
+#[borsh(crate = "near_sdk::borsh")]
+pub enum StorageKey {
+    Ideas,
+    Solutions,
+    Attestations,
+    Sponsorships,
+    Comments,
+    Posts,
+    PostToParent,
+    PostToChildren,
+    /// Deprecated due to damaged storage state.
+    LabelToPosts,
+    LabelToPostsV2,
+    AuthorToAuthorPosts,
+    AuthorPosts(CryptoHash),
+    Communities,
+    AddOns,
+    Proposals,
+    LabelToProposals,
+    AuthorProposals,
+    RFPs,
+    LabelToRFPs,
+    RFPLinkedProposals,
+    LabelInfo,
+}