Add 2021-04-01 SRP api version (Azure#14211)

* Create 2021-04-01 SRP api version, no features

* Adding Blob Inventory GA Swagger changes and examples

* Add Container VLW Swagger changes

* Add Lease Share (Commit 1204774b: Merged PR 4370500: Swagger: deleted share with leased snapshot; lease share; share ACLs; list both deleted shares and snapshots; allow cross tenant replication; default share permission)

* Add custom-words, Add default responses for new apis

* Capitalize VNet rule state

* Update Descriptions for the Blob Inventory Properties.

* Address Description change to make BI schema fields value Name as always required.

* Update BI descrption

* Add 201, 202 response types to FileshareLease Acquire and Break functions, updated examples

* Update pending readme files, correct spellcheck in file.json

* Add LeaseShareRequest model as string and x-ms-longrunning

* Add long running tag to vlw migrate api, remove 202,201, long running tag from FileLeaseShare

* Change VLW migration PUT to POST, Add longrunning tag to location, update blobInventory filter prefixMatch descr and removed required field, date-time format for Lease share

* Change LastAccessedTime to LastAccess time schema field

custom-words.txt

@@ -903,6 +903,7 @@ Iscsi
 iscsiservers
 isdir
 isdirectory
+isfolder
 ishostingenvironmentnameavailable
 ishostnameavailable
 isnullable
@@ -1968,6 +1969,7 @@ uniquestring
 unitless
 unixtime
 UNKNOWON
+unleased
 unlocalized
 unmanaged
 unmonitored